Bought a house, since gas in house already and our family generally anti-oil took some bids for oil to gas conversion. Interesting to see how different the approaches were. House is 1450sq feet, unfinished basement, 2 full bath in Long Island NY. 1 zone heat. We rarely use simultaneous draws for hot water. I take short showers, wife takes 10-15 min showers. We might shower back to back on occasion but usually spaced out. Kid takes baths standard sized tub. At most laundry might be running at the same time as a shower/bath. Dishwasher runs at night. We travel a bit so at times there is simply no hot water demand for weeks at a time. Water is not hard, as far as I can tell. Generally 2 bids said 105-120BTU boiler with standalone direct fire 45-50 gallon hot water heater. I'm generally not fond of stand alones from an efficiency and longevity standpoint though they were asking ~$1100 less. The others were boilers attached to indirects. One was Techtanium TT-40, another was an aquaplus 45 and the final one that I am most interested in is the TurboMax 23. I guess before jumping the gun, -Is an indirect the way to go for my usage? Factoring the $1100 difference, I can have the a stand alone fail basically and replaced for the cost of the indirect. -Second the TurboMax in particular was the lowest bid so the one I am considering the most. I can't find a lot on them especially recent info except they are supposed to last a long time unless you have hard water.... -Finally for the indirects most recommended a higher btu boiler but the TurboMax guy kept it at the 105BTU. Issues? Also have one bid for a System 2000 which seems great in theory except it was $3k more for the oil version and $5k more for the gas.... Which economically doesn't make sense and then I'm afraid I'll be tied to them when no one wants to service it...

This sounds like a good application for a combi boiler setup. You will get on demand heating and on demand DHW without needing a storage tank.

How is the house heated? Radiant, baseboard, Forced air?

Baseboards. Or technically one true baseboard stretch then 7 other convector radiators which are like the baseboards (just a pipe with fins) elevated in enclosures. Seemed really dumb to me from a space perspective as it is literally a pipe through a 3 by x metal box.... But the house came this way..

After more reading I feel like these should be my options
-High Mass Boiler with a Tankless (boiler off during summer)
-Low Mass Boiler with an Indirect (boiler runs in summer)
-Combi (boiler runs all the time)

So in my above questions probably a high mass 85% burnham isn't the best match for a TurboMax....
Also most of my bids were with 85% AFUE boilers though I see low to mid 90% AFUE. What is the pay back on that difference?

A typical 2x4 framed 1450' house on L.I. has a heat load less than 25,000 BTU/hr, which makes a 100K boiler ridiculously oversized for it's primary load.

Low mass combi-boilers are usually a TERRIBLE fit for a small house with a low heat loads, yet modest to average hot water loads. Most will short-cycle on baseboard zones due to insufficient heat emitter at minimum fire. The minimum-fire output of some combi-boilers may be close to your actual heat load, and can't be operated in condensing mode without severe short-cycling.

How many feet of baseboard?

How tall & wide are the convectors, and the size of the finned tube?

Is it all one zone?

Have you been there long enough to have some wintertime gas bills on which to run a fuel-use based heat load calculation?

http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new

High mass combi-boilers can be a decent solution (HTP Versa: http://www.htproducts.com/versahydro.html ), which are inherently short-cycle proof due to the thermal mass of the water in the tank, and MUCH better insulated than an oversized cast-iron beast with a tankless coil.

A low mass boiler (sized for the heating load) + indirect can be pretty efficient, but takes more space than a high-mass combi.

What is your current heating method?

If the same fuel you might be able to take the years sum of your current heating bill and multiply it by (old efficiency / new efficiency)

So say you pay $1000 a year to heat and your old broiler was 60% and new is 85%
(.6 / .85 ) * $1000 = $705 or a saving of $295 dollars per year.

You can then take that $705 which represents you new bill to amount to calculate pay backs.

so, .85 / .9 * $705 = $665 so you would save $40 per year buying the more efficient model.....

Hope this helps.....hope it is correct also so someone check my math, I am not a expert.....and am sometimes an idiot..

Newbostonconst, your math is indeed correct!

One can also use software like this to determine and compare different fuel and efficiency heat source option operational costs:

Borst Integrated Heating System Performance Software

Posted By Dana1 on 16 Apr 2018 04:54 PM
A typical 2x4 framed 1450' house on L.I. has a heat load less than 25,000 BTU/hr, which makes a 100K boiler ridiculously oversized for it's primary load.

Low mass combi-boilers are usually a TERRIBLE fit for a small house with a low heat loads, yet modest to average hot water loads. Most will short-cycle on baseboard zones due to insufficient heat emitter at minimum fire. The minimum-fire output of some combi-boilers may be close to your actual heat load, and can't be operated in condensing mode without severe short-cycling.

How many feet of baseboard?

How tall & wide are the convectors, and the size of the finned tube?

Is it all one zone?

Have you been there long enough to have some wintertime gas bills on which to run a fuel-use based heat load calculation?

http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new

High mass combi-boilers can be a decent solution (HTP Versa: http://www.htproducts.com/versahydro.html ), which are inherently short-cycle proof due to the thermal mass of the water in the tank, and MUCH better insulated than an oversized cast-iron beast with a tankless coil.

A low mass boiler (sized for the heating load) + indirect can be pretty efficient, but takes more space than a high-mass combi.

Hmmm maths. All 5 bids from local contractors suggested boilers in the 105-120k BTU range. Not saying they are right or not but just that they were unrelated businesses that made these recommendations. I theorize that many push certain product lines and the small boilers were too small so they go the next one up... Most were only 85% AFUE so net BTUs closer to mid 80s. I thought I read 50 BTUs per sq ft which equates to 72500. The guy I chose actually measure each of the baseboards and the convector radiators and came up with 67k BTUs needed for heat. I think his recommended boiler only puts out net 77k BTUs. A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters. Also potentially may add small addition or finish basement... In terms of baseboard there is only 18ft that look like baseboards. The remaining 7 convector radiators are (to me at least) essentially the same thing - a pipe with fins attached to it - only that it sits in the middle of housings that vary from 2-3ft tall to 18" (bathroom) to 5 ft (main bedroom). Picture a pipe in a large metal rectangle with slits in it. Guessing maybe an 1inch tube??? Weird to me at least... I expected full on radiators having been an apt dweller my whole life.

Haven't been there a winter. Back story is that sellers left me no oil in the tank. When I called for a service call/prime/flush/restart and the requisite 100 gallon minimum drop they wanted to charge a literal arm for that so wife and I took some oil to gas conversion bids. We are semi anti oil anyway having lived in residences with oil heat...

I went back and forth with the company doing the work. He was recommended by my friend and also came in lowest price wise. A lot of people seem to have the opinion to go with what the installer is comfortable with seeing that good equipment installed badly is in many cases worse than average equipment installed correctly. Anyway he explained to me that we could go any way I wanted but most of the higher efficiency stuff required mandatory yearly service and in his mind had a higher incidence of issues than what it was worth in terms of payback. What I lose in fuel I get back in less likelihood of service calls. And I like having things that people actually have parts for... We ended up with a Burnham ES2-4 and a Bradford White direct fire 50 gallon. He seems to think I could basically have one fail and still come out ahead vs any of the other options - combi's, indirects, etc. Only time will tell I guess... Not very glamorous... But in line with my wish for tried and true over super finicky but higher efficiency.

Posted By newbostonconst on 16 Apr 2018 04:55 PM
What is your current heating method?

If the same fuel you might be able to take the years sum of your current heating bill and multiply it by (old efficiency / new efficiency)

So say you pay $1000 a year to heat and your old broiler was 60% and new is 85%
(.6 / .85 ) * $1000 = $705 or a saving of $295 dollars per year.

You can then take that $705 which represents you new bill to amount to calculate pay backs.

so, .85 / .9 * $705 = $665 so you would save $40 per year buying the more efficient model.....

Hope this helps.....hope it is correct also so someone check my math, I am not a expert.....and am sometimes an idiot..

Thanks newbostonconst!!! Will use that for new calcs in the future.

Original was oil. But I haven't been in there long enough for an actual heating cost numbers. Bought the house and they left me no oil. Oil company wanted basically what ended up equating to 10% of my oil to gas conversion estimate to come/flush/prime/restart and mandatory 100 gallon drop. The old boiler was 20 years old, said 143 MBH : D.O.E. HTG CAP, 124 MBH : NET powering the heat and an indirect. Firing rate listed 1.25 GPH. No Input number that I see though so I can't reverse calculate the efficiency. Also several inspectors noticed a mis mash of parts already attached to it and to the indirect storage tank. With gas already in the house makes sense in my mind at least to swap.

Posted By honda99ex on 17 Apr 2018 01:06 AM

Posted By Dana1 on 16 Apr 2018 04:54 PM
A typical 2x4 framed 1450' house on L.I. has a heat load less than 25,000 BTU/hr, which makes a 100K boiler ridiculously oversized for it's primary load.

Low mass combi-boilers are usually a TERRIBLE fit for a small house with a low heat loads, yet modest to average hot water loads. Most will short-cycle on baseboard zones due to insufficient heat emitter at minimum fire. The minimum-fire output of some combi-boilers may be close to your actual heat load, and can't be operated in condensing mode without severe short-cycling.

How many feet of baseboard?

How tall & wide are the convectors, and the size of the finned tube?

Is it all one zone?

Have you been there long enough to have some wintertime gas bills on which to run a fuel-use based heat load calculation?

http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new

High mass combi-boilers can be a decent solution (HTP Versa: http://www.htproducts.com/versahydro.html ), which are inherently short-cycle proof due to the thermal mass of the water in the tank, and MUCH better insulated than an oversized cast-iron beast with a tankless coil.

A low mass boiler (sized for the heating load) + indirect can be pretty efficient, but takes more space than a high-mass combi.

Hmmm maths. All 5 bids from local contractors suggested boilers in the 105-120k BTU range. Not saying they are right or not but just that they were unrelated businesses that made these recommendations. I theorize that many push certain product lines and the small boilers were too small so they go the next one up... Most were only 85% AFUE so net BTUs closer to mid 80s. I thought I read 50 BTUs per sq ft which equates to 72500. The guy I chose actually measure each of the baseboards and the convector radiators and came up with 67k BTUs needed for heat. I think his recommended boiler only puts out net 77k BTUs. A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters. Also potentially may add small addition or finish basement... In terms of baseboard there is only 18ft that look like baseboards. The remaining 7 convector radiators are (to me at least) essentially the same thing - a pipe with fins attached to it - only that it sits in the middle of housings that vary from 2-3ft tall to 18" (bathroom) to 5 ft (main bedroom). Picture a pipe in a large metal rectangle with slits in it. Guessing maybe an 1inch tube??? Weird to me at least... I expected full on radiators having been an apt dweller my whole life.

Haven't been there a winter. Back story is that sellers left me no oil in the tank. When I called for a service call/prime/flush/restart and the requisite 100 gallon minimum drop they wanted to charge a literal arm for that so wife and I took some oil to gas conversion bids. We are semi anti oil anyway having lived in residences with oil heat...

I went back and forth with the company doing the work. He was recommended by my friend and also came in lowest price wise. A lot of people seem to have the opinion to go with what the installer is comfortable with seeing that good equipment installed badly is in many cases worse than average equipment installed correctly. Anyway he explained to me that we could go any way I wanted but most of the higher efficiency stuff required mandatory yearly service and in his mind had a higher incidence of issues than what it was worth in terms of payback. What I lose in fuel I get back in less likelihood of service calls. And I like having things that people actually have parts for... We ended up with a Burnham ES2-4 and a Bradford White direct fire 50 gallon. He seems to think I could basically have one fail and still come out ahead vs any of the other options - combi's, indirects, etc. Only time will tell I guess... Not very glamorous... But in line with my wish for tried and true over super finicky but higher efficiency.

Sizing the heating system to 50 BTU/hr per square foot will reliably heat an air leaky uninsulated shack with single pane windows at 0F. Real heat loads of 2x4 framed houses with so-so insulation and clear glass storms over wood sash single panes are only about 1/4- 1/3 that much, and it matters!

Measuring up the radiation is a necessary part of designing the system, but is not the way to size the boiler. The 67,000 BTU/hr is the most heat that the existing radiation can emit, and is by definition MORE than the actual heat load. Putting a 100K/85% boiler on radiation that can only emit 67K doesn't heat the house any faster, but it guarantees that during long calls for heat the boiler will be cycling on/off at a duty cycle rather than burning continuously. Installing a 77K boiler on that radiation will result in a higher duty cycle during continuous calls for heat, but won't improve the overall seasonal duty cycle sufficiently to overcome the standby losses. With every ignition cycle there is a hit in efficiency, and every interval between burns there is a standby loss.

"A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters." A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters.

That is THE most common error in judgment with boiler sizing. With high-mass boilers oversizing even a little actually DOES hurt (a bit), and oversizing by a lot hurts a LOT! The increase in cycling and standby losses goes up rapidly when the average seasonal duty cycle is less than 20%, which it's guaranteed to be if you're at 2x oversizing. At 2x oversizing you'd have enough burner (but not necessarily enough radiation) to heat the place to 70F indoors at an outdoor temperature of -40F, and outdoor temperature not seen on Long Island since the last ice age. ASHRAE recommends no more than 1.4x oversizing, which is more than enough to cover the load during Polar Vortex type cold snaps. AFUE testing presumes 1.7x oversizing.

For some data behind the effects of oversizing, see: https://www.bnl.gov/isd/documents/41399.pdf

If the radiation delivers 67K at high temp it would still be able to deliver 12-15K at condensing temperatures. So a low mass combi boiler COULD in fact work in this system as long as it's minimum-fire output is in the 15,000 BTU/hr range or lower, and operated as a single zone.

Looking it up, the Burnham ES2-4 actually delivers 89,000 BTU/hr DOE output, which is well above your radiation can even emit, and is at least 3x oversized for the whole-house heating load. Using the IBR output of 77K isn't legit unless the boiler is on the other side of an insulated wall (say in the garage) from the conditioned space, with a presumed ~13-15% of the heat being lost outside of conditioned space. With the boiler in the basement it is by definition inside of conditioned space, where any standby and distribution losses from the boiler and plumbing are still supporting the heat load, not truly lost.

The negative effects of the oversizing will be blunted a bit due to it's standard equipment heat purging boiler control, but the ES2-3 still would have been the more appropriate choice, even though it can "only" deliver 59,000 BTU/hr, not quite hitting the absolute maximum that the radiation can deliver (but probably still more than 2x your heat load, still enough to carry the load at -50F or whatever.)

It probably would have been cheaper up front (and better comfort overall) to install a simpler fire-tube modulating condensing boiler such as the HTP UFT-080W and a 40 gallon indirect. That particular boiler can still deliver the 67KBTU/hr should the next ice age begin sooner than anticipated, but can also throttle back to ~7500 BTU/hr. Set up properly under outdoor reset control it would track the heat load with nearly continuous burns and very little on/off cycling, delivering very stable room temperatures and higher comfort.

Building out the basement at code-minimum R values or building a code-min addition usually LOWERS the whole house heat load. The boiler that was installed can heat three older houses that size well into negative digits F, and a handful of new code-min houses that size with reasonable margin against cold snaps.

Posted By Dana1 on 17 Apr 2018 08:23 PM
Looking it up, the Burnham ES2-4 actually delivers 89,000 BTU/hr DOE output, which is well above your radiation can even emit, and is at least 3x oversized for the whole-house heating load. Using the IBR output of 77K isn't legit unless the boiler is on the other side of an insulated wall (say in the garage) from the conditioned space, with a presumed ~13-15% of the heat being lost outside of conditioned space. With the boiler in the basement it is by definition inside of conditioned space, where any standby and distribution losses from the boiler and plumbing are still supporting the heat load, not truly lost.

The negative effects of the oversizing will be blunted a bit due to it's standard equipment heat purging boiler control, but the ES2-3 still would have been the more appropriate choice, even though it can "only" deliver 59,000 BTU/hr, not quite hitting the absolute maximum that the radiation can deliver (but probably still more than 2x your heat load, still enough to carry the load at -50F or whatever.)

It probably would have been cheaper up front (and better comfort overall) to install a simpler fire-tube modulating condensing boiler such as the HTP UFT-080W and a 40 gallon indirect. That particular boiler can still deliver the 67KBTU/hr should the next ice age begin sooner than anticipated, but can also throttle back to ~7500 BTU/hr. Set up properly under outdoor reset control it would track the heat load with nearly continuous burns and very little on/off cycling, delivering very stable room temperatures and higher comfort.

Building out the basement at code-minimum R values or building a code-min addition usually LOWERS the whole house heat load. The boiler that was installed can heat three older houses that size well into negative digits F, and a handful of new code-min houses that size with reasonable margin against cold snaps.

Thank you much Dana1 for your wisdom.

I think that's exactly it. For the ES2-3 you are quoting the DOE numbers of 59, contractor used the NET rating of 51 and said too low, thereby moving up to the ES2-4. That was his rationale. But you are telling me that number is already at least 1.7x what the house can currently support. RIght? The boiler will live in an unfinished basement so will be losing heat only into the "conditioned" not actually heated space.

Well I think the boilers has been ordered so spilled milk there. What can I do with the extra BTUs? (only half kidding) Bigger radiators? Additional radiators? Turn heat into multi-zone? Indirect tank in future? Heat my neighbors house? =(

This is just another good example of how heating systems end up being over-sized by 2–3 times by most HVAC companies.

Posted By sailawayrb on 17 Apr 2018 09:21 PM
This is just another good example of how heating systems end up being over-sized by 2–3 times by most HVAC companies.

First time homeowner. I thought I was doing my due diligence by taking 5 bids from local contractors.... But why do they do that? What do they gain? A small initial premium on a larger boiler?

A combination of lack of knowledge, overly conservative and higher commission from larger sale.

Posted By Dana1 on 17 Apr 2018 06:27 PM


Sizing the heating system to 50 BTU/hr per square foot will reliably heat an air leaky uninsulated shack with single pane windows at 0F. Real heat loads of 2x4 framed houses with so-so insulation and clear glass storms over wood sash single panes are only about 1/4- 1/3 that much, and it matters!

Measuring up the radiation is a necessary part of designing the system, but is not the way to size the boiler. The 67,000 BTU/hr is the most heat that the existing radiation can emit, and is by definition MORE than the actual heat load. Putting a 100K/85% boiler on radiation that can only emit 67K doesn't heat the house any faster, but it guarantees that during long calls for heat the boiler will be cycling on/off at a duty cycle rather than burning continuously. Installing a 77K boiler on that radiation will result in a higher duty cycle during continuous calls for heat, but won't improve the overall seasonal duty cycle sufficiently to overcome the standby losses. With every ignition cycle there is a hit in efficiency, and every interval between burns there is a standby loss.

"A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters." A little surplus never hurt and I'd rather have more than not enough given the extreme weather now that falls under design parameters.

That is THE most common error in judgment with boiler sizing. With high-mass boilers oversizing even a little actually DOES hurt (a bit), and oversizing by a lot hurts a LOT! The increase in cycling and standby losses goes up rapidly when the average seasonal duty cycle is less than 20%, which it's guaranteed to be if you're at 2x oversizing. At 2x oversizing you'd have enough burner (but not necessarily enough radiation) to heat the place to 70F indoors at an outdoor temperature of -40F, and outdoor temperature not seen on Long Island since the last ice age. ASHRAE recommends no more than 1.4x oversizing, which is more than enough to cover the load during Polar Vortex type cold snaps. AFUE testing presumes 1.7x oversizing.

For some data behind the effects of oversizing, see: https://www.bnl.gov/isd/documents/41399.pdf

If the radiation delivers 67K at high temp it would still be able to deliver 12-15K at condensing temperatures. So a low mass combi boiler COULD in fact work in this system as long as it's minimum-fire output is in the 15,000 BTU/hr range or lower, and operated as a single zone.

So I did an actual heat loss calculation using the burnham US Boiler site. The windows and doors I ballparked but shouldn't be off by much... The rest of it I used the actual house survey numbers so it should be fairly accurate.
Total Heat Loss for 60 degree F temp diff = 59,296
THL for 70 degree F temp diff = 66,429.28
THL for 80 degree F temp diff = 75,436.64
THL for 90 degree F temp diff = 84,444
THL for 100 degree F temp diff = 93,451.36
That's using infiltration factor as moderate based on blower score test/average house
And basically middle of the road insulation parameters...
Now I don't if I'm interpreting it correctly but most boiler manufacturers recommend using 70 degree F temp diff. So using that number the Burnham ES2-4 should be correct since it says mostly use NET number but always greater than the heat loss never below it.
Right? But you are saying that the reality is really 1/3 of that???? Not trying to be a pain... just want to speak to my contractor with some semblance of knowledge... Thanks you all
PS I actually did it several different times with slightly different numbers but the THL at 70F temp diff was always in the 55000-66000 range....

Posted By sailawayrb on 17 Apr 2018 10:55 PM
A combination of lack of knowledge, overly conservative and higher commission from larger sale.

Sailawayrb
I don't know how to multi quote but check out my post above on heat loss.
That's how many choose their boilers correct? or is that an out dated methodology?
And by that method the low Burnham would be just a wee bit too small, and the next one above a bit too big.
Do you feel the Burnham ES2-4 is overkill for my needs? Like just terrible unacceptable or just uses a bit more fuel than desired??? Do you feel as Dana1 that a ES2-3 would work better? or is that improperly sized too?
Thanks!!!!

I don't understand how you got your heat loss analysis delta T? The delta T is normally the difference between 68F (i.e., code indoor design temp) and your local 99% dry bulb temp (i.e., code outdoor design temp). I suspect the delta T you used is larger than it should be. Where are you located?

Been crazy busy today and I haven't had time to read this thread completely and estimate your heat loss, but based Dana's comments which I fully trust, I would say that you have grossly over-sized your heat source.

Posted By sailawayrb on 18 Apr 2018 03:00 AM
I don't understand how you got your heat loss analysis delta T? The delta T is normally the difference between 68F (i.e., code indoor design temp) and your local 99% dry bulb temp (i.e., code outdoor design temp). I suspect the delta T you used is larger than it should be. Where are you located?

Been crazy busy today and I haven't had time to read this thread completely and estimate your heat loss, but based Dana's comments which I fully trust, I would say that you have grossly over-sized your heat source.

i went here http://www.usboiler.net/heat-loss-calculator.html
it asks for the house dimensions and the window/door sq ft, then factors in insulation and infiltration. Crude approximation
I live in Long Island. So I guess I should use a delta T of 53-58? Online I think Eastern LI may have used 10F as a design while Western LI/NYC uses around 15F.
So I should use the Total heat loss at 60F maybe lower... Which likely if I extrapolate should be in the mid 40s. Are I getting warmer lol on my understanding? A boiler should be picked to handle THL?

Yes, I would agree that is a very crude heat loss estimate... You would be better off having a ACCA Manual J or even just using something like this:

Borst Heat Loss Analysis Software

Or doing an existing building energy usage analysis like this:

Borst Existing Building Energy Usage Analysis Software

You can get outdoor design temps here:

ACCA Outdoor Design Conditions

53F seems like a more reasonable delta T. ASHRAE recommends getting a heat source 40% larger than the actual heat loss at the local 99% dry bulb temp. The thinking here is largely to accommodate nighttime thermostat setback...getting a larger heat source to handle heating up the typical house furnishings in addition to the air in the morning in a reasonable amount of time. If you have a high interior thermal mass house (e.g., concrete slab floors and masonry walls, etc.), you should NOT use nighttime thermostat setback. As a house becomes more energy efficient (i.e., is well-insulated and well-sealed), the benefit of using nighttime thermostat setback tends to zero. If you don’t use nighttime thermostat setback, I would NOT recommend applying this 1.4 factor to the heat loss estimate for sizing the heat source.