Posted By 532nm on 23 Jan 2014 05:43 PM
Would anyone recommend for the time being to turn off my DSH until I get a storage tank installed? Is this relatively easy to do? I've contacted my plumber for a quote on a storage tank. Any recs on size and model?

Dana1, looked into the mini-split but I don't like the aesthetic value of the mini-split system.

Aesthetics are just one of several reasons why tacking on a ductless is less than ideal.  There are often ways to mount 'em so you don' have to look at 'em, but not always.  (The aesthetics of your bank statements need to be balanced against other considerations too, eh? )

Hopefully this will sort out as a minor design implementation screw up, and not a major under-sizing issue.  But it's going to be hard to figure out without a lot more information than what has been posted to date.

Posted By SkyHeating on 23 Jan 2014 06:53 PM
I think along with your HVAC contractor getting you a heat loss for the home, you need to find out more about your loop. I would have them give you the Entering Water Temperature (EWT) and Leaving Water Temperature(LWT) to see how your loop is performing. It could be that your loop is close to hitting freeze protection so your unit is not producing the amount of heat it is supposed to and thats why aux heat is coming on. Typically 1 bore hole per 1 ton of system, since you have a 5 ton system you should have 5 bore holes at about 200' each(depending on ground conditions and pipe size). For a high efficiency home(without knowing heat loss) it is possible that a 5 ton system can heat 6,000 sq feet, but that home better be VERY tight and well insulated(sorry I don't know what a HERS rating is) but it sounds like that is your home.

I will echo the others that you should have a 50 gallon preheat tank for your geo system, click on my Youtube link below to see some videos of systems or my WEL server to see a diagram of a desuperheater storage tank.

A HERS rating is an energy use estimate comparing the rated house against an IECC 2006 code-min house of equivalent size.

A HERS rating of 44 should only use 44% of the energy of a typical new construction home that size.

So the fact that this place is sucking juice like a wino instead of a teetotaler sneaking a sip means that either the HERS rater was incompetent, or there's something amiss with the mechanical systems, or some combination thereof.

Posted By ChrisJ on 22 Jan 2014 02:01 PM
3 vertical wells at 150', sounds like a rule of thumb design for 3 tons.

You'd be in real trouble in a Dallas climate designing to this 'rule of thumb.'  Not sure if you'd have much heat absorption capacity left in the borehole field after 5 years.  Bill

Posted By dgbair on 24 Jan 2014 07:37 AM

...

There is a nice diagram posted by Bergy.

I'd put this in the GBT's Hall of Fame.  The diagram leaves nothing to interpretation on how to exactly implement the buffer tank.  It's a classic.  Has probably been posted over 100 times - it's in the archives.  Bill

Posted By SkyHeating on 23 Jan 2014 06:53 PM


I will echo the others that you should have a 50 gallon preheat tank for your geo system, click on my Youtube link below to see some videos of systems or my WEL server to see a diagram of a desuperheater storage tank.

Thanks for making your wel public. Could you let us know where the sensor for your buffer tank is located? I am curious about the apparent low heat gain of the buffer tank.

A couple things raise red flags.

1) The lack of curtesy of your installer.

2) If you really have 3 x 150 ft boreholes in there, you might have a significant issue.

3) No buffer tank questions the expertise of the installer. You essentially make 90% of your hot water with electric resistance heat

4) Balance point is the outside temp when the geo cannot keep up anymore. 72F is the inside design temperature. Again, with your size house, your normal electricity bill is probably around $200, plus $300 for geo in the coldest month in years. Not too bad. I would say to get a buffer tank, which should shed off $30-$40/month. Check on your loopfield size. Other than that it should be all fine.

Posted By docjenser on 26 Jan 2014 04:08 PM
A couple things raise red flags.

1) The lack of curtesy of your installer.

2) If you really have 3 x 150 ft boreholes in there, you might have a significant issue.

3) No buffer tank questions the expertise of the installer. You essentially make 90% of your hot water with electric resistance heat

4) Balance point is the outside temp when the geo cannot keep up anymore. 72F is the inside design temperature. Again, with your size house, your normal electricity bill is probably around $200, plus $300 for geo in the coldest month in years. Not too bad. I would say to get a buffer tank, which should shed off $30-$40/month. Check on your loopfield size. Other than that it should be all fine.

I agree, I can't believe we are 3 pages deep without establishing something is actually wrong.

I'm not guessing. If you only had 3 loops at 150 ft depth your 5TON GEO UNIT WOULD NOT RUN so most likely whoever told you that was guessing. If you are maintaining over 70 degrees throughout the home the machine is functioning, 10kw backup heaters couldn't keep 6000 sq ft to that temp and 20kw heaters might do it but would run almost nonstop and cost over $900/mnth at your rate. The desuperheater does not have to be hooked up. Climatemaster always install them but Waterfurnace leaves it as an option, also I add a switch to turn the "DSH" off during the winter to any geo unit without a factory installed switch. The "DSH" is ONLY intended to preheat your domestic hot water, so in the winter instead of losing heat needed by your air to your water you save money by turning it off. If your water heater does heat your loop water it would increase your geo units heating capacity which wouldn't be a bad thing this year at all. I would have suggested two units at least at 8-10 total tons for a 6000 sq ft home, that being said if your home has maintained 70 degrees through THIS winter you have a good system. A buffer tank is used for water to water geo units and boilers to reduce short cycling of the equipment, a hot water storage tank is often connected to the "DSH" and is the best way to get full benefit from the "DSH" but does not HAVE to be used. I didn't read all of your posts because you were getting some bad info and I got tired of reading posts from people who were either partially or entirely guessing. I hope your home did stay as warm as you wanted it to and if it did you can expect lower energy usage in the years to come when temps are normal. A 6000 sq ft home I have serviced for the past few years has a 4ton geo, a 2 1/2 ton geo console, two 60,000 BTU water to air heat exchangers(one on top the 4 ton and one on a second floor High Velocity air handler) and two high efficiency boilers all playing roles in heating the home. Their bill last month was $575 total. A 14,000 sq ft home I designed the system for uses four 4 ton units, I'm not sure how their bills are this winter because they haven't had any troubles so I haven't been there. One post I read was at least on the right track, +6 is very close to the design temp where I operate an HVAC business and I would estimate your homes heat load to be at least 125KBTU and a "BALANCE POINT" of 0 to -10 degrees at that load. I always "oversize" systems to hold set temp down to -18 to -25 but use 2 stage equipment for reasonable operational costs. Your unit is a 2 stage 5 ton geo(T=tranquility+T=2stage+V=verticalunit and -064=64,000BTUor5tonsforshortwhichisactually5and1/3tonsas12,000BTUs=1ton) so if my load GUESS(ok so that is a guess but I don't have time or enough info to give you a real load calc) is right than at +6 outdoor temp your home would not hold temp. If you have a 20kw heater it produces about 68,000 btus so your home would start losing temp when the actual load of your house is 95,000 to 120,000 BTUs as the heating capacity of the unit itself is 35 to 50 thousand BTUs. When your home couldn't keep your set temp that was the "balance point" if you have a 10kw it was 60,000 btus or so if you have 20 kw it was over 95,000 and if your home kept temp your contractor did a great job.

Posted By htgguy on 08 Feb 2014 07:15 PM
I'm not guessing. If you only had 3 loops at 150 ft depth your 5TON GEO UNIT WOULD NOT RUN so most likely whoever told you that was guessing. If you are maintaining over 70 degrees throughout the home the machine is functioning, 10kw backup heaters couldn't keep 6000 sq ft to that temp and 20kw heaters might do it but would run almost nonstop and cost over $900/mnth at your rate. The desuperheater does not have to be hooked up. Climatemaster always install them but Waterfurnace leaves it as an option, also I add a switch to turn the "DSH" off during the winter to any geo unit without a factory installed switch. The "DSH" is ONLY intended to preheat your domestic hot water, so in the winter instead of losing heat needed by your air to your water you save money by turning it off. If your water heater does heat your loop water it would increase your geo units heating capacity which wouldn't be a bad thing this year at all. I would have suggested two units at least at 8-10 total tons for a 6000 sq ft home, that being said if your home has maintained 70 degrees through THIS winter you have a good system. A buffer tank is used for water to water geo units and boilers to reduce short cycling of the equipment, a hot water storage tank is often connected to the "DSH" and is the best way to get full benefit from the "DSH" but does not HAVE to be used. I didn't read all of your posts because you were getting some bad info and I got tired of reading posts from people who were either partially or entirely guessing. I hope your home did stay as warm as you wanted it to and if it did you can expect lower energy usage in the years to come when temps are normal. A 6000 sq ft home I have serviced for the past few years has a 4ton geo, a 2 1/2 ton geo console, two 60,000 BTU water to air heat exchangers(one on top the 4 ton and one on a second floor High Velocity air handler) and two high efficiency boilers all playing roles in heating the home. Their bill last month was $575 total. A 14,000 sq ft home I designed the system for uses four 4 ton units, I'm not sure how their bills are this winter because they haven't had any troubles so I haven't been there. One post I read was at least on the right track, +6 is very close to the design temp where I operate an HVAC business and I would estimate your homes heat load to be at least 125KBTU and a "BALANCE POINT" of 0 to -10 degrees at that load. I always "oversize" systems to hold set temp down to -18 to -25 but use 2 stage equipment for reasonable operational costs. Your unit is a 2 stage 5 ton geo(T=tranquility+T=2stage+V=verticalunit and -064=64,000BTUor5tonsforshortwhichisactually5and1/3tonsas12,000BTUs=1ton) so if my load GUESS(ok so that is a guess but I don't have time or enough info to give you a real load calc) is right than at +6 outdoor temp your home would not hold temp. If you have a 20kw heater it produces about 68,000 btus so your home would start losing temp when the actual load of your house is 95,000 to 120,000 BTUs as the heating capacity of the unit itself is 35 to 50 thousand BTUs. When your home couldn't keep your set temp that was the "balance point" if you have a 10kw it was 60,000 btus or so if you have 20 kw it was over 95,000 and if your home kept temp your contractor did a great job.

Welcome! Interesting "novel" points of view…. Here are a few thoughts!
1) Let me assure you that a 5 ton can run very well with 3x150 F pipe. All you need is 1.25" pipe, ensuring enough flow. Then, if you have a nice conductivity, some underground water stream or a lesser than 5 ton load on the house, and you 5 ton heatpump will work fine with that loopfield.
2) 10KW =34KBTU can keep a 6000 sqf house up to temp, it depends on the heatloss of that 6000 sqf house!
3) Both Climatemaster and Waterfurnace units can be ordered with and without DSHs
4) The DSH does not only preheat but can make your entire hot water during months with a long run time. My second tank does not turn on in the winter time, the DSH makes my entire hot water (Family of 5 plus visitors).
5) Why is it good to turn off the DSH? Then you make your hot water not with the efficiency of the geosystem but with whatever your secondary source efficiency is.
6) Why would you want to heat your cold ground with the hot water you just generated? Rejecting heat from the house/ hot water tank to the ground in the heating season?
7) Why bothering to put in a DSH system when you do not "HAVE" to do this in an efficient way. DHW consumes a large amount of energy, and having only a 1 tank DSH setup ensure that the vast majority of hot water is made without the effiency of the geosystem.
8) So you suggest a 2 unit system, 8-10 tons, without knowing the load? We have a lot of 6000 sqf houses running on 5-6 tons...
9) Interesting that you got tired of folks here either partially or entirely guessing…..
10) It is good to know that you always oversize your systems. Just don't let your customers know that you spent so much more of their money upfront.

Welcome htg guy.
You make a terrific amount of assumptions while suggesting others are making bad guesses. Those pros who have been around here for awhile have learned to try to fill in blanks as often people do not provide all the information we need (inspite of being asked multiple times and a checklist stuck to the top of the forum).
Perhaps you have something useful to share, but so far you are off on the wrong foot.

Waterfurnace puts a switch on their units so it can be turned off during winter, they told me that in one of the classes I took from them, to maximize heating output. I'm aware you can request no desuperheater on a Climatemaster, the geo consumer posting the inquirer we are responding to seemed to think it helped heat the house as I understood it and to help illustrate it wasn't essential I pointed out they don't all come with it. I'm not sure why you didn't notice but I ended my post, very intentionally, with that if the home keeps temp the contractor did a great job. My closing statement was made based on that I don't know the load, which I stated earlier in my post as well, but guessed it. I learned from Rick Rahaim, a geologist employed by WFI as a trainer, that using all inch and a quarter lines does require less pipe but increases pumping requirements. The best insulated 6000 sq ft home with best everything would have a heat load higher than 35,000 BTUs for sure, so while I don't know the exact load I am sure a 10 KW heater alone couldn't keep this house to temp. It's obviously not docjenser's first day, nor is it my first day, energystar ratings allow 130% of calculated heat load which I prefer to use. While I have designed systems from 4 to 96 tons, all of which hold set temp to well below zero, I have fixed more systems than I designed and unless a system didn't have enough pumping capability you can't do anything for an undersized system. I was referring to the company rep when I said the loopfield size was a guess, docjenser also made a statement questioning the reported loopfield. My bids are what they are, if a customer requests a bid for less than what I think is adequate for their home I decline the work. But you don't need to worry about my customers sir, I give them fare prices up front, keep their homes comfortable for low operating costs and would never turn my back on them.

Inquiry not inquirer, oops

Joe, I see you are in Michigan, are there 6000 sq ft homes in your area with loads low enough for a 5ton system? I am in Iowa and haven't seen that size of a home that would keep up with a 5!ton unit.

Posted By htgguy on 09 Feb 2014 11:28 AM
Joe, I see you are in Michigan, are there 6000 sq ft homes in your area with loads low enough for a 5ton system? I am in Iowa and haven't seen that size of a home that would keep up with a 5!ton unit.

It all comes down to doing a good job of calculating the heat loss for the particular house. A newly constructed house, built to superinsulated level (eg. the "Pretty Good House," as presented over on greenbuildingadvisor.com) of 6,000 sqft likely could be kept warm in Zone 6 with a three-ton GSHP. I base this on results of my own house, of close to 4,000 sqft and heated by a two-ton Climatemaster Tranquility 27, without having to go to second stage, down to -3 F. I posted some numbers on this over on GBA recently. For new construction, I always advocate putting the first money into a really good exterior shell, well beyond code-minimum, before looking for a cheap way to heat it.

Apologies to all for being a bit hot headed. Now I've read all posts and can add some better input. With 4000 sq ft first floor and what we call an "ice block" foundation around here I agree with docjenser that 5-6 tons should be adequate. And as long as the 5 ton keeps up, it's the less expensive to operate. What I still haven't seen is an answer to " does the home keep up to your set temp?" I don't agree that auxiliary should come on at <30 degrees. I use my geolink program to make final sizing decisions, it alerts if the system won't keep up and I size the unit so a 10kw heater plus unit will maintain temp at -18. The program usually shows my system will cost a couple hundred more per year than one that starts losing set temp closer to zero but I HATE BEING COLD. My statement about losing heat to the loop was a bit hasty as well, I actually don't understand how it would happen. To transfer heat from the DHW to the ground the water in the desuperheater would have to lose heat to the hot gas, then the refrigerant would have to not reject the heat to the air and then the refrigerant leaving the TXV would have to be warmer than the loop water. ????? To the geo customer, I think we all would have to agree your usage is high. I would venture to say that with aux coming on at 32degrees you should have lost temperature at some point this winter. Maybe unless you have a 20kw auxiliary heater and if you do it is my opinion the unit is a bit undersized. I hope the winter has gone well for you and that your HVAC contractor has resolved any problems you may have had.

Posted By htgguy on 09 Feb 2014 11:12 AM
Waterfurnace puts a switch on their units so it can be turned off during winter, they told me that in one of the classes I took from them, to maximize heating output. I'm aware you can request no desuperheater on a Climatemaster, the geo consumer posting the inquirer we are responding to seemed to think it helped heat the house as I understood it and to help illustrate it wasn't essential I pointed out they don't all come with it. I'm not sure why you didn't notice but I ended my post, very intentionally, with that if the home keeps temp the contractor did a great job. My closing statement was made based on that I don't know the load, which I stated earlier in my post as well, but guessed it. I learned from Rick Rahaim, a geologist employed by WFI as a trainer, that using all inch and a quarter lines does require less pipe but increases pumping requirements. The best insulated 6000 sq ft home with best everything would have a heat load higher than 35,000 BTUs for sure, so while I don't know the exact load I am sure a 10 KW heater alone couldn't keep this house to temp. It's obviously not docjenser's first day, nor is it my first day, energystar ratings allow 130% of calculated heat load which I prefer to use. While I have designed systems from 4 to 96 tons, all of which hold set temp to well below zero, I have fixed more systems than I designed and unless a system didn't have enough pumping capability you can't do anything for an undersized system. I was referring to the company rep when I said the loopfield size was a guess, docjenser also made a statement questioning the reported loopfield. My bids are what they are, if a customer requests a bid for less than what I think is adequate for their home I decline the work. But you don't need to worry about my customers sir, I give them fare prices up front, keep their homes comfortable for low operating costs and would never turn my back on them.

Sure there is a switch on the WF. The DSH takes about 10% capacity away for DHW, so there might be applications where you want to shut it off, like being on vacation or increasing the capacity for your space condition. But not generally advisable since now you stop making your DHW with the efficiency of your geo unit. Higher capacity of your Space conditioning should come from supplement heat not from shutting off the DSH.

The geologist who told you that 1.25" increases pumping requirements should read up on on pressure drop whereas larger pipe requires lesser pumping power based on lesser pressure drop.

While I questioned the loopfield described here, you made general statements that it cannot work, which is not the case. The similar general statement was made by you that 35KBTUs cannot heat a 6,000 sqf house.

You simply made a lot of untrue statements for someone who has designed up to 96 ton system, which I hope you did not do with the geolink software, which is for smaller residential system design.

Nobody suggests being cold here, but to accept such a gross oversizing which means much higher capacity than needed will result in higher upfront costs for the customer compared to a smaller system, no matter how you fair you say your prices are.

You are wrong docjenser. You can type whatever you want it still won't keep a house to 70 degrees in -10 degrees with a 30 mph wind unless it's some kind of house that isn't built around here. If there is such a house and I'm not aware of it, your lack of informing is probably indicative of a character defect of yours. I said I was sorry, get over it. And you have no clue who I am, your assumptions of my heating skills based on one dumb statement shows you will say something when you don't know what you're talking about. Why should I or anyone take your advice on anything. NEVERMIND!!!!!! CUSTOMER, I STRONGLY SUGGEST IF YOU NEED MORE ASSISTANCE TO GET IT FROM ANOTHER FORUM. DOCJENSER, NO NEED TO STROKE YOUR OWN EGO BY INSULTING ME AGAIN I HAVE BETTER THINGS TO DO THAN ARGUE WITH YOU, BYE

Htg guy,
You don't know what you don't know. I mentioned before you may have something to add, but you instead criticize and attack. Some before you even read what we are commenting on.
A shame you didn't read Doc's and my post before you weighed in which suggests little could be wrong if the heating bill for this 6,000SF is $300ish.
Again we have to ferret out information from non responsive posters.

If you are truely a student of geo, you can learn a lot from hanging around here (as have I). Aside from Doc, contributors from other professions (i.e. Dana and Bill) have educated me to a point where the service to my clients has vastly improved as has my design strategy.

WF may tell you to turn off a DSH, but they (as do other manufacturers) also tell you you don't need a buffer tank which is bull. There are many wives tales in this business and your WF rep is no less susceptible to them than any one else.

Stick around, put some monitors on your systems and watch them perform in real time, get the chip off your shoulder and learn.

Btw the OP hasn't been around since 23 Jan. Another thing you'll learn is that people get resolution and are never heard from again, so your comments to the OP (original poster) are falling on deaf ears.

Posted By htgguy on 10 Feb 2014 12:35 AM
You are wrong docjenser. You can type whatever you want it still won't keep a house to 70 degrees in -10 degrees with a 30 mph wind unless it's some kind of house that isn't built around here. If there is such a house and I'm not aware of it, your lack of informing is probably indicative of a character defect of yours. I said I was sorry, get over it. And you have no clue who I am, your assumptions of my heating skills based on one dumb statement shows you will say something when you don't know what you're talking about. Why should I or anyone take your advice on anything. NEVERMIND!!!!!! CUSTOMER, I STRONGLY SUGGEST IF YOU NEED MORE ASSISTANCE TO GET IT FROM ANOTHER FORUM. DOCJENSER, NO NEED TO STROKE YOUR OWN EGO BY INSULTING ME AGAIN I HAVE BETTER THINGS TO DO THAN ARGUE WITH YOU, BYE

The house in question in this thread has HERS rating of 44-  it's not a standard code-min type of house.

There are houses built all over N. America to specs that would rate significantly lower than HERS44 (say R2000 houses, Net Zero Energy houses, and certified PassiveHouse houses), and if you seek them out, you'll probably find some "around here" (defined as within an hour's drive of your US ZIP code) in all but a very few locations.  Got  ZIP code?

With that I could probably dig up web-references to such houses in the 'hood.  A mere HERS44 house probably isn't interesting enough to get blog write-ups.  R2000 houses in Canada don't get individual attention either, but they are out there, and in significant numbers.

It doesn't take a super-insulated PassiveHouse house to have a heat load a -10F with a 30mph wind to have a heat load within the output of 5 tons of geo or even 3 tons, but no, it's not a "typical" house anywhere (yet.)