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Old 11-16-11, 07:51 PM   #1
orange
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Default Gas fired condensing hot water tank for hot water and radiant heat

After researching most of the possible simple, affordable and efficient avenues to heat our little old house I have decided to go with a gas fired condensing hot water tank. They seem to run about $2000, are up to 96% efficient, and are dual duty heating and hot water. They can also be used with solar hot water systems and I'm assuming heat pumps as well. Another advantage is that we will not have to upgrade our gas lines and they are much simpler to install than a tankless unit.

I did consider a heat pump but did not want to go with a forced air system and there are difficulties with finding an air to water heat pump that can do radiant water heat. Also then we would still need a hot water heater. And there's the problem of when it's too cold for the heat pump.

The gas hot water tank allows us to get going cheaply and augment later when we have scads of cash to get a heat pump that can do the job of air to hot water heating.

The major hardware chains do not carry these high efficiency tanks yet although I saw a heat pump hot water heater. Kind of silly if you put one of these inside because you would just be stealing heat from your house to heat the water.

Anyone here had experience with these condensing gas units or where to get them in Canada for a reasonable price?

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Old 11-16-11, 09:10 PM   #2
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Quote:
Originally Posted by orange View Post
...I have decided to go with a gas fired condensing hot water tank. They seem to run about $2000, are up to 96% efficient, and are dual duty heating and hot water.
I've looked at those too, pretty good way to go, I think.

I'd like to see the specifications on the unit you've found.

Quote:
Originally Posted by orange View Post
...there are difficulties with finding an air to water heat pump that can do radiant water heat. Also then we would still need a hot water heater. And there's the problem of when it's too cold for the heat pump.
There is a unit that will do air to water, and it will do hot water too, and it's range of operating conditions is quite impressive. Unfortunately, so is it's price, but new tech usually come down, eventually (like after you've spent all your money).

But the unit is called the Daikin Altherma

Quote:
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...later when we have scads of cash to get a heat pump that can do the job of air to hot water heating.
I think you pretty much understand the price point for one of these puppies.

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...heat pump hot water heater... stealing heat from your house to heat the water...
If you live in a moderate, marine type climate, a heat pump water heater would be a pretty good fit, for heating water.

However, it might not handle heating your house, unless your house is on the small size and is very well sealed and insulated.

It sounds like you already have the radiant installed, in the floor I would presume?

Do you already know how much heat it takes to get you through Janurary?

How many square feet is your place and how well is it insulated?

Have you looked at how much sustained heat output your condensing water heater is capable of?

I live in Portland, Oregon, so my weather picture is probably similar to yours.

So up your way, what does a 'cold snap' look like? How cold will it get, and how many days will it hang on?

Also, there is a heating calculator you might want to check out, too, for comparison purposes.

Best,

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Old 11-16-11, 09:44 PM   #3
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We live in the Fraser Valley east of Vancouver so it's pretty moist and mild. Cold snaps are usually about -5C and maybe last a week. The rest of the time its around 5-10C and raining.

GDHE-50-NG - AO Smith GDHE-50-NG - 50 Gallon - 100,000 BTU Vertex 100 Power Direct Vent Residential Gas Water Heater (Nat Gas)

Have not done the BTU calculations yet but we are adding to this house. I think there are three units available up to 250,000 btu.(just checked and there only seems to be a 75000 and a 100000)

Total will be about 1700 square feet in 2.5 floors so its a nice small footprint. The first floor will be new construction so I may do something super high r-value there.

I'm in the process of insulating the existing floor right now. Will probably green-it foam the cathedral roof parts as they are only 2x4 construction. The rest will be batts or cellulose.

I wish we could find a dense pack capable machine here but most the contractors I have talked to don't even know what dense packing is. I like the fact that the dense pack acts as an air barrier because we don't want to gut the whole place to seal it tight. I'm leaning towards loose fill cellulose in the new 2x6 walls with resiliant clips as thermal break and sound control.

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Old 11-16-11, 11:29 PM   #4
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We bought the smaller 90% efficient A.O Smith Vertex water heater and I figure it will have paid for it's self in 5 to 6 years, or less and that is assuming that our near wore out water heater would last that long.
I'm really impressed with it and thought about the heat pump water heaters as well, but what turned me away from them was that they required a warm humid utility room to draw heat out of and that if it was not heating the water as quickly as it thought it should it would revert back to a heating element.
The plus side is that it cools your warm humid basement and makes it cool and dry, perfect for food storage and in my area it would cost about the same to run as natural gas, a little more maybe but the 10 year outlook would be about the same over all cost.
Things I like about the A.0. smith vertex is that it heats water super fast, I own a duplex with a single water heater and it's good for over 3 gallons per minute forever, it also has a fan that plugs in that allows for a cheap lamp timer to be installed to turn it off at night, saving a few cents per months because this water heater costs $2.75 per month to heat water 24/7 compared to $20+ per month for the electric tank water heater.
I bought it from a place online that offered free shipping, I called around and asked if anyone could price match and the closest was $200 more... if it was $50 or less I would have gone for the local place but really? I can do a lot of good with $200.

Last edited by Ryland; 11-16-11 at 11:38 PM..
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Old 11-17-11, 12:18 AM   #5
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Sold!

The first one I came across, the Polaris, I found some bad reviews on so it's good to hear from an actual user. Not the same unit but close enough.
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Old 11-17-11, 07:38 AM   #6
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I choose that water heater after talking to a number of friends, one who installs solar hot water systems and another that heads up the low income energy efficient retrofits that I've mentioned on here before and both of them right away said that the A.O Smith Vertex water heater was the way to go and I never really found a good 2nd choice.
The friend who installs solar hot water systems looks to install a handful of these water heaters per year, I installed mine my self and found it to be really straight forward.
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Old 11-17-11, 11:35 AM   #7
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Hello all,
A previous house I had used an Apollo Heating system that got its heat from a gas fired water heater, and had an air handler in the attic, with 3/4" or 1" cpvc pipe from the heater up to the air handler. It worked well, though I cannot remember just how effecient it was, I thought it worked pretty well. I'd do one again if I had gas into my house.
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Old 11-18-11, 01:21 AM   #8
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Called a local plumbing supply today and got the Canadian prices for the 50 gal 100000btu vertex (~$2400) and the 34gal 100000btu Polaris (~$2500). I was surprised that the Polaris is only $100 more because it has a stainless tank. The vertex has a 6 year tank and a 6 year parts warranty and the Polaris has a 10 year tank but only a 1 year parts warranty. Hmmmm. Lots to ponder.

I read in another post that someone got one of these supplied and installed for $2000! Good deal.
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Old 11-18-11, 07:24 AM   #9
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GDHE-50-NG - AO Smith GDHE-50-NG - 50 Gallon - 100,000 BTU Vertex 100 Power Direct Vent Residential Gas Water Heater (Nat Gas)

Is where I got mine from, not sure if the free shipping is good to Canada.
That 6 year warranty worried me a little as well, but it's a warranty for commercial use, so the glass lining should be good for well past 6 years, although in theory a stainless tank should last decades if built right.

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