I'm currently looking to get rid of the natural gas heating in my home and replace it with something carbon neutral.

This is a personal choice for me, but once that is out of the way, I am still trying to determine the best way to go with replacing and updating my existing heating system.

Currently my home has about 1200 sq feet heated by electric baseboards on the top floor, and around 3000 square feet on the main floor and basement heated by a natural gas forced air furnace, as well as a gas water heater. I'm located in Vancouver BC, so the climate is mild in the winters, but occasionally gets down to the -10 C range.

The simplest thing would be to just replace the gas furnace and water heaters with a GSHP or possibly an air source heat pump and electric water heaters.

However, the house is also a bit of a heat trap in the summer with large west facing windows (facing a view) that lead to large heat gain in the afternoon and evening, so we would like to do something about cooling the upstairs sleeping area as well. Also, the baseboard heating is just unsatisifying from an efficiency point of view.

I've had one company recommend two air source heat pumps, with an air handler installed in the attic (Zuba by Mitsubishi), and I also have an initial proposal in hand for a dual GSHP system with a climate master Tranquality 27 replacing the furnace, and an additional water to referigerant heat pump hooked up to a high velocity air coil in the attic.

Outside of the price of drilling, the two approaches have similar costs, although the high velocity air hander adds a bit of a premium, and the air source solution does not give me any boost for water heating. Note that both of these options would mean installing a system of ducts in the attic, and locating an air handler of some kind in the attic.

Are there any other options that I am overlooking and should be considering? I also got a quote on a mini-split system for the top floor, but with 5 rooms the numbers from the local suppliers didn't look that good compared with the other options.

Also, I'm trying to do some lifetime ownership costing, and I'm having a pretty hard time finding any data on the real expected lifetime of either ground or air source heat pump equipment. I'd like to know the expected lifetime of different choices so I can account for the expected frequency of replacement.

Any advice and sources of extra information much appreciated.

yeesh that's one long paragraph.......

IMO, you have many things going on at once.
1) trying to achieve carbon neutrality
2) trying to cool the house
3) you are likely trying to get a little payback out of the new equipment ( "Also, the baseboard heating is just unsatisifying from an efficiency point of view.")

Because you are getting air conditioning added to your upstairs, some of the usual approaches to calculating pay back have to factor the value added to your home.

I'm not as easily convinced of the "green" side of geo in many cases, but it is certainly better than electric baseboard as it de;ivers an average of 3.5 times the heat with a like amount of energy.

Here are some of other the answers you need.
Geo generally lasts longer than other kinds of equipment.

Geo will still contribute to your heat when it is -10f out. ASHP's will not.

I don't know how you will be able to get around a duct system in the attic (unless you want to gut the ground floor of your home).

High velocity systems are often more for installer convienience than necessity. There is always more than one way to skin a cat and since HV is a little more expensive and less efficient than conventional duct systems. I would get more opinions on how best to accomplish your goals.

Before putting an airhandler in an attic, I like to look for alternatives (i.e. build a chase or take a closet to get a main trunk to the basement).

Remember best geo guy does not automatically mean best duct guy. You may want to hire different contractors for different stages of your project.

Good luck,
Joe

Hi Joe,

Thanks for your response. Good food for thought.

First, sorry about the paragraphing in the intial post. Apparently you need to use Internet Explorer with this forum. My original paragraphing got lost, and I added it back several times. This time I switched browsers and it appears to have stuck.

Generally speaking I'm willing to consider a number of other options than Geo here to achieve my goals, although the technology geek in my likes Geo, so I'm watching out for by own bias that way.

I'll dig a bit more into the question of high velocity vs. other duct approaches, and I'll see if I can get some quotes on extending the existing duct system upwards. Is there a general consensus that ducts are more efficient than other approachs to delivering heat and cooling, e.g. per room radiant water heating and cooling, or per room air handlers ala a mini-split? It seems to me that less moving parts is better, so mini-splits don't seem like the best option from a long term hardware cost point of view, but I don't have enough real information to determine that.

Is there any more specific information about the general life time of different kinds of equipment? Its pretty hard to plug "longer" into a spreadsheet :)

Should I expect 10 years from an air source heat pump? 15? 20? Same for geo equipment. What I'm trying to determine is ignoring the cost of fuel is there a case to be made that over the long run putting in a geo field means spending less money on heating equiptment causing it to balance out, and if so over what time period does it balance out.

Thanks again for your answers so far, apprecaite your time.

Cheers,

-- eric

 

Ducts in the attic isn't ideal, you might find hydronic with either baseboards (heating only) or small, in the room (or wall) hydronic air handlers easier.

I've been a bit less than enthusiastic about ducts in the attic as well, and also less than enthusiastic about having an air handler in the attic that I have to go up and change filters on. I was going to get a contractor to look at running something up from the basement in a series of closets that happen to align with the furnace below, and more or less come out on top of the existing manifold, so perhaps we could extend the ducting from there without needing to redo all the ducting on the main and basement. This could then shoot sideways below the ceiling and get to most of the space that needs heating with only lowering the ceiling a bit in closets and bathroom spaces. This seems attractive from the point of view of only needing one heating/cooling appliance in the basement, but I'm not sure yet if the heating load will allow for this even if the duct work does. Initial calculations are calling for about 6 tons of heating, and I'm not sure we can get a single unit that does 6 tons. Maybe we can invest in some other improvements that get us down to 4-5 tons total though. I think we could also run hot and cold water up the same space and then between rooms maybe behind a crown molding or small chase. What should I be looking for / asking for in terms of hydronic air handlers? The only thing I've been able to find is some units by multi-aqua? What sort of problems does one run into with hydronic air handlers in terms of maintainable and reliability? One piece of hardware in each room is more to fail, but if the expected lifetime is good I'm happy to absorb the occasional independent failure and replacement costs for individual units. Cheers, - eric

Some here also: http://www.pdhvac.com/pioneer/index.php/hydronic-fan-coil-units/156

You could retain your nat gas furnace for the peaks and then make very efficient use of a smaller geo system.

joe- he never sees -10F in Vancouver (ever), but sometimes sees -10C (+14F), which is well within the efficient operating range of Daikin and a few other cool-temp air source heat pumps. IIRC the 99% heating design temp for Vancouver B.C. is something like 18-20F, a temp where the hydronic version (Altherma) puts out ~25KBTU at a COP north of 3.0. (The heat load at my house at -10C is less than 25K- YMMV. But my design temp is closer to -20C.)

see: http://thermalproductsinc.com/wp-content/uploads/2010/06/Daikin-Altherma-Engineering-Data1.pdf

http://www.daikinac.com/DOC/ALTH-ENWP11-03%20-%20Daikin%20Altherma%20Overview%20Paper.pdf

You could probably retrofit radiant flooring or low temp panel radiators for less than the difference in upfront cost between one of those and geo-air system which would also be more comfortable. The same panels could be used for sensible cooling without much condensation risk in Vancouver's climate too.

Are there any similar products with more heat capacity? Right now I'm estimating my heating load based on HDD data from local weather stations (averaged between stations taken over the last year) and my metered gas and electric usage. I'm guessing at the moment that at -10C my heating load is going to be somewhere around 50-60K. I can probably do some work to improve that [I'm scheduling an assessment on that now], but I'll be surprised if we can take the existing structure down to 25K. Of course, I suppose we could top up with electric heat, and I'll have to look and see if I can extrapolate from the weather data how much energy that would take. We don't get down to -10C that often. Anyone have real experience with the noise level on the Daikin units? Is it as good as the data appears to be? Also, given then relatively recent nature of these low ambient heat pumps, how concerned should I be about possible problems with reliability? Last question, anyone know of any Canadian suppliers, better yet, in the lower mainland area of BC? I haven't been able to find anything with a quick google search.

Anyone have any comments on the experience of retrofitting hydronic units like this into an existing home? From what I can see a lot of places would run the water lines through the attic (presumably under the insulation)? I presume these are lines with a an anti-freeze in the mix as well just in case? Anything special I should be watching out for with bids from contractors? Should I be looking for specialists in hydronic installs for this separate from the heat pump installer?

Posted By eschenk on 05 May 2011 01:42 PM
Are there any similar products with more heat capacity? Right now I'm estimating my heating load based on HDD data from local weather stations (averaged between stations taken over the last year) and my metered gas and electric usage. I'm guessing at the moment that at -10C my heating load is going to be somewhere around 50-60K. I can probably do some work to improve that [I'm scheduling an assessment on that now], but I'll be surprised if we can take the existing structure down to 25K. Of course, I suppose we could top up with electric heat, and I'll have to look and see if I can extrapolate from the weather data how much energy that would take. We don't get down to -10C that often. Anyone have real experience with the noise level on the Daikin units? Is it as good as the data appears to be? Also, given then relatively recent nature of these low ambient heat pumps, how concerned should I be about possible problems with reliability? Last question, anyone know of any Canadian suppliers, better yet, in the lower mainland area of BC? I haven't been able to find anything with a quick google search.

The Daikin units can put out a lot more heat than 25KBTU/hr using the resistance heat backup.

Unless your house is very large &/or the leakiest least-well insulated home in Vancouver with lots & lots of glazed area, mostly single pane there's no way your house is going to be anything like 55-60KBTU/hr @ -10C.   And if the house IS a leaky wreck usually a lot cheaper to upgrade the air-sealing, glazing etc to knock it down by at least 1/3 that it is to add the additional capacity as geothermal.

If you use summertime power use to calculate a rough background load on the electricity use and back that out of your wintertime power & gas use, it's pretty straightforward to use your gas & power usage, along with the steady-state combustion efficiency of the gas burners against heating degree day data to arrive at a fairly accurate design condition heat load.  It only get's tricky if you're using wood stoves or live in a high-sun area (not exactly the typical Vancouver type winter climate, eh? ;-) ) with a lot of south facing glazing where you'd have to factor out those inputs as well.

The Altherma has been available in Japan & Europe for more than 5 years now, but only recently in N. America.  ( IIRC Sanyo(?) has a similar product available in Asia & Europe that used CO2 as the refrigerant.)  Daikin has been in the air conditioning business for 60 years, and has been doing refrigation for more than 85 years.  There's nothing dramatically different between their new vs. old stuff,  or their other mini/multi splits etc, just some refinements in design, and designing toward a lower-temp outdoor operating spec than cheap 1-stage heat pumps.  NRT.Rob (posts on the radiant heating forum on this site) has one heating his office in Gardiner Maine, (where the outdoor heating design temp is about -22C), and could fill you in on some of the details & options.

There is at least one installation of the Altherma in Portland OR, and there are several Daikin distributors in WA, but I'm less sure how deep they are into B.C. . There is at least one HVAC contractor in Vancouver handling Daikin heat pumps.  While they may or may not have installed the Altherma (yet), there's no special sauce about it that makes it very different from other heat pump systems. It would not require a huge amount of training on their part.  They may have to rent low temp hydronic/radiant heating design expertise to handle the radiation-end of the design (they seem to be primarily a fan-coil type HVAC company), but low-temp hydronic design expertise is SURELY available in So.B.C..

It's not a cheap solution, ~$15KUSD + radiation, call it ~18K-22K depending on whether you retrofitted in some radiant floor or did it mostly with low-temp panel radiators,  but would be as-efficient as geo in your climate, at around half to 2/3 the installed cost of geo.  It would almost certainly to be cheaper to operate than a gas furnace too.

Thanks the response. I'll look up the the local guys you found.

The house is a bit on the large side, depending how I cut things up. If I include the garage, which I would like to heat, I've got close to 4800 square feet. Without the garage it's closer to 4200 square feet.

There is also a lot of glass. It's all dual pane, but, for example, there is a two story 12 foot wide 18 foot tall view wall in the living room facing north west that is mostly glass, and generally the entire north west side of the house is large windows to take advantage of the view.

A rough guess at the window area on the view side of the house is 400 square feet of glass. There is probably another 150 in the rest of the house.

Additionally, because this is BC lower main land, when the house was built 2x4 walls were allowed for houses heated by natural gas. The house is a mix of 2x4 and 2x6 that I haven't quite been able to understand yet. The valuted livingroom is 2x6 framing, probably because of the height of the room. The rest appears to be all 2x4 walls. A really rough calculation based on best guesses on some items gets me a calculated heat loss of about 70k on a DTD of 58 degrees F, but I'm not exactly an expert at the calculations, although I know my way around a spreadsheet and have a degree in math, so I understand the principles. My best guess is that we tend to do a bit better than that in practice looking at the heating bills, and I'm defintely going to look at what we can do to improve the heat loss, but the size of the house is an issue.

In any case, I'll be consulting a professional service to take some measurements and make recommendations, if only because that's the path to getting government grants.

One question: where you thinking that the daikin unit would feed an air handler for the portion of the house that currently has forced air, or are you suggesting that I should put radiant panels in place of that system?


Cheers,

-- eric

With a sizable glazed are and a 4800' house you might be looking at a 55K heat load. A real manual-J type heat loss calc or a careful analysis of your fuel & power use against heating degree-day weather history could also get you there. It's only 1.5-2x the size of my house for floor area, and heat loss doesn't increase linearly with floor area, only with exterior surface area (shape counts.) Reality might be under 50K, but probably not under 40K @ -7C.

To run with a fan coil & air handler using the existing ducts with comfortable exit-air temps (>35C, >40C even better) you'd have to run the Altherma's output hotter than 50C, and efficiency would suffer. With enough low-temp radiation (such as above-the subfloor tubing radiant floor) in place you could run it at 35-40C output for the space heating and achieve a higher COP.

Even if the Altherma on it's own falls short of the design condition load, the average heat load is far less than -7C (your 97.5% design temp) design condition output, and it's COP and total output increases at the higher temps. Average January temps are above +2C, a temp at which the Altherma can deliver 35KBTU+ with a COP of 4. That's also temp at which (assuming a 55K heat heat load with 20C indoors, -7C outdoors) your heat load is within the full output of the compressor if you go with the largest one.

It's VERY likely that there is some low hanging fruit in the form of air sealing and spot insulation upgrades that would bring your design condition heat load under 50K too.

You might see if this freebie spreadsheet heat loss tool gives you a better handle on it: http://www.crownboiler.com/Support/Education/Boiler-Sizing

(note, the design temps in the ODT tab are the 97.5% values, which lists +19F for Vancouver.) Play around with the air-infiltration factors too, not just the window size/type and wall insulation. I've not tested this tool for accuracy, but it's got to be way better than a WAG.

So I ran a couple of different calcs last night just for fun.

I pulled together my electric and gas bills along with the HDD and CDD data for the last 16 months, and did a multiple linear regression analysis to tease out cooling costs (we have a window air conditioner we use in the master bedroom in the summer so we can sleep) from winter heating on the electric bill, and a simple linear regression fit on the gas bill accounting for the months I keep the furnace turned off.

That comes out with a design load of about 40k BTU for a DTD of 53 F, which seems very good, but I can't see a hole in the regression analysis. The intercept I calculated on the gas bill almost exactly matches the gas usage in the middle of the summer, when it is only used for cooking and hot water heating. Perhaps I should be assuming that all the heat from gas makes it's way into the home regardless?
If I do this, I come back with a design load of about 50k BTU on a DTD of 53F.

Using the spreadsheet you mention above, I get a much larger number, but I made some approximations around the building shape that should be corrected for. Also the spreadsheet seems to me to do something very sketchy around infiltration losses, and I when I corrected it with the calc's for specific heat and densitity of air I get something a bit closer to what my billing is showing me.

I used the tool here: http://www.builditsolar.com/Referen...atLoss.htm and got a number around 58k BTU on DTD of 53F. However, I think the treatment of my basement in this tool is probably incorrect, especially since the basement starts out fully underground and slopes to fully exposed at the back.


Interestingly, if I assume that all the electric power eventually makes its way into heat, I get a number that is much close to 58k BTU, but I'm not at all sure of the thermo dynamics of that situation. I suppose that in practice at least most of the electricity consuming appliances in my home actually genearte a fair bit of waste heat (electronics and and lighting for the most part), so perhaps that's fair?

Looks like we would have to do a fair bit of retrofitting of low temp radiant heat to effectively use the Daikin unit, especially once I start accounting for hot water, and throwing in another 10k BTU to heat the garage. In that case, it sounds like two units would be a better plan, one for the forced air unit, and one to supply water based heating for the upper floor and garage, but I don't know how that compares yet to the option of getting a single 5 ton geo heat pump and having it feed both water heating and an air handler.

I've got someone coming by tomorrow to take a look at retrofit options for water based high wall air handlers and/or radiant panels. I'll see what kind of numbers they come up with and how that comparse to the pricing of attic air ducts. Gotta say I rather like the idea of avoiding putting anything in the attic though if I can avoid it.

Thanks again for everyone who has helped provide information so far.

Posted By Dana1 on 03 May 2011 05:55 PM
joe- he never sees -10F in Vancouver (ever), but sometimes sees -10C (+14F), which is well within the efficient operating range of Daikin and a few other cool-temp air source heat pumps. IIRC the 99% heating design temp for Vancouver B.C. is something like 18-20F, a temp where the hydronic version (Altherma) puts out ~25KBTU at a COP north of 3.0. (The heat load at my house at -10C is less than 25K- YMMV. But my design temp is closer to -20C.)

Ahhh yes 10C.
Mahbad
Have we a monitored airsource system showing 3+ COP at 20 degrees F?
j

In that case, it sounds like two units would be a better plan

If you are fine with two units, you might consider making one of them a Ductless mini-split air source heat pump.

I am putting a Daikin Altherma system in a 7000 sf home about 50 mi South of you, but we still get the Fraser River blasts. I'm putting it together with a Ductless mini-split to increase my options. That should also allay any concerns over capacity and placing the remote units can help with difficult ducting issues.

So I've ended up with another company looking at the geothermal side of things as well as some options on the low tempurature radiant water side of things.

He ended up declining to provide an option on the low temp. radiant side on the basis that he felt there was not enough space in our utility room for the necessary 120 gallon hot and cold buffer tanks to run water based heating and cooling in the house together with an air handler, heat pump and domestic hot water system. The utility room is pretty limited, about 6 feet wide and 12 feet long, and there is a laundry hookup in there as well.

After looking over the house, this fellow suggested two other possibilities.

One was to go with four smaller 1/2 ton geothermal heat pumps on the 2nd floor, basically water to air units that could be located in the upper part of the closet space in each bed room. This has the advantage of smaller ducting requirements, but does mean a more complex flow system. With this option it looks like we would still need a couple of short (12-15 foot) duct runs to deal with distributing some heat to the far end of some larger rooms.

The other option is to put a 2 ton geothermal water to air heat pump on the 2nd floor in some existing closet space, and run a small amount of ducting from this into the rooms that need heating. Given the room configuraiton, two of the four rooms can be heated from this closet space without a duct run, which would leave us needing to place two small runs into the attic for the master bedroom and the upstairs living room, or at least into some kind of chase near the ceiling. This at least gets the hardware out of the attic. How much should I be concerned with ducts (only) running though the attic?

One other question that occured to me, the other contractor I had out to talk geothermal initially wanted to put 2 ton water to DX in the basement, and a DX to air in the attic. Is there a special concern about running a water line to a heat pump upstairs vs. running a DX line upstairs that might motivate this? Noise? Water damage vs. coolant leak damage? Something else?


Back on the hot water side of things, anyone have any thoughts on the limitations presented by the size of the utility room? Do I need to take low temp radiant off my shopping list, or is there a reasonable way around this?

Thanks again for all the thoughts from everyone.

Posted By joe.ami on 07 May 2011 07:16 PM

Posted By Dana1 on 03 May 2011 05:55 PM
joe- he never sees -10F in Vancouver (ever), but sometimes sees -10C (+14F), which is well within the efficient operating range of Daikin and a few other cool-temp air source heat pumps. IIRC the 99% heating design temp for Vancouver B.C. is something like 18-20F, a temp where the hydronic version (Altherma) puts out ~25KBTU at a COP north of 3.0. (The heat load at my house at -10C is less than 25K- YMMV. But my design temp is closer to -20C.)

Ahhh yes 10C.
Mahbad
Have we a monitored airsource system showing 3+ COP at 20 degrees F?
j

NRT.Rob's experience in monitoring the Altherma (installed last summer) at his office this heating season is that it has been beating efficiency expectations slightly.  He's revised his numbers a few times when sensing errors were discovered, but there's plenty of reason to believe it's at least roughly what the spec sheet says it is.  In Rob's case he may be getting a performance edge over spec by having designed the radiation for somewhat lower operating temps than where the spec-sheet parameters on the Daikin are taken.

Posted By eschenk on 05 May 2011 01:42 PMAnyone have real experience with the noise level on the Daikin units? Is it as good as the data appears to be?

Your post is a month old but I'll answer anyway.  I have a Daikin VRV-S 36,000 Btuh air to air heat pump. The outdoor unit is adjacent to my patio. The only time it is somewhat noisy is in the winter when it's in heating mode and the fans are running full speed. Not many people sit on the patio during the winter so the noise level then is a non issue! During the summer most of the time it is running far less than full bore and is quiet. Even during heavy cooling time you can easily converse sitting within a few feet of the unit. When it's running at low load the compressor hum is loader than the fans. In fact, the other day when I walked past it the first indication I had that the unit was running was the warm air blowing off the coils! All in all, it is a very quiet unit, and I have no regrets whatever about having parked it next to the patio.