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Should I replace boiler for radiant heat?

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Joined: Jul 18 2009

Our eichler was built in 1958 and still has the original boiler and radiant heat. I am considering replacing the boiler but should I spend $6-7k ? I have been told my pipes are not copper. Am I living on borrowed time for the original radiant heat pipes? Would my money be better spent just putting in a different type of heating system through the house? If I thought there was a high probability my radiant heat would work for another 10yrs, I would buy the new boiler... but if I'm on borrowed time and am more likely going to be looking at jackhammering concrete to fix leaks - seems like replacing boiler is a waste. Confused.

Tod
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Joined: Mar 21 2003

All I have to offer are opinions and speculation. Give it the little weight it deserves.

1. Most Eichlers had copper radiant heat systems. The exception being those built when there was a copper shortage. Our 1958 Eichler definitely has copper radiant heat piping. I'd be surprised if others built in 1958 were not copper. Are you sure your pipes aren't copper?

2. If the system has been sealed, then corrosion should be minimal. (The dissolved gasses react with the environment and become neutralized, only when fresh water with fresh dissolved gasses are introduced to the system do you get more corrosion. So you don't want to leave leaks unfixed.)

3. The primary cause of leaks on a copper system is the slab shifting. If your slab has not shifted/cracked in 50 years, then it should be good indefinitely.

Given the above, I personally think that if your pipes are good now, they should be good for a long time to come. So the question isn't how long your pipes are going to last but how long do you plan on owning the house.

We replaced our original 1958 AO Smith boiler two years ago. Not because it stopped working. And not because it was cheaper to do so once you look at the cost of a new boiler versus the cost of gas saved over the expected life of the new boiler. Our reason was that natural gas was, and to a certain extent still is, the biggest source of CO2 from our household. More than our cars, more than our electricity.

Gas bills on Eichlers depend on lots of factors: How warm you like the house to be. The exposure on the windows in relation to the winter sun, how much insulation retrofitting has been done, etc. Our gas use, even with the AO Smith, was significantly less than what we have heard other Eichler owners experience, even within our own neighborhood that has the same micro-climate. During the last two winter heating seasons the new Munchkin Contender boiler seems to use about 30% to 50% less gas than the old AO Smith. Even with that gas savings, we will not recover the installation costs of the new boiler before the end of the expected life of the new boiler.

So, if you have a broken boiler: Replace it with a high efficiency modern one.

If your boiler is working and you are going on cost alone, spend your money on insulation and weatherizing your house.

If your boiler is working and you've done all the weatherizing and insulation you can and you are worried about your carbon footprint, then look into a new boiler.

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Joined: Jul 18 2009

Excellent advice, thank you so much. I'm wondering if there is a definitive way to tell if my radiant heat pipes are copper or steel. I will figure this out and report back. The house is in North Terra Linda in San Rafael.

Joined: Apr 17 2007

I'm not sure if I can offer a definitiveway to see if your radiant pipes are copper, but when we bought our 1958 Eichler, the radiant heat inspector had a method. He had a somewhat strong magnet that he held up to the radiant pipes that entered the slab underneath the boiler. If the magnet stuck, the pipes were galvanized steel. Since the magnet did not stick to our pipes under the boiler, he then moved to the radiant heat manifold, which in our model, is located in the hallway closet. He then applied the magnet to those pipes, and once again, the magnet did not stick, which indicated that the pipes were copper. (The greenish patina on the manifold also seemed to say copper as well.)

At the time, I was not that satisfied, since I was bent on only buying an Eichler that has copper radiant pipes. Since then, I have been told that there is no easy way to join galvanized and copper pipes together, indicating that we probably have a full copper system. Our house is located in the Lower Lucas Valley neighborhood, which has a mix of houses with copper and galvanized pipe radiant systems. I have also heard that 1958 was the year that most houses went back to copper piped radiant heat systems. I hope this helps!

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Joined: Jul 18 2009

This was helpful, thanks. I had a fellow eichler owner come over. We walked to the hall closet, looked at the manifold. He is a civil engineer by trade, builds commercial buildings for a living and is a pretty handy guy to boot. We looked at the manifold, it also had the greenish patina on the manifold which he also indicated was a sign it was copper ... he scratched a little off w/ a knife and said, "this is copper." He also said that would indicate that all the pipes in the slap would be copper as well (for the same reasons you mentioned). That said, it looked like the big pipe, which is the intake valve from the boiler into the manifold, was galvanized steel - and had been repaired. That pipe, of course, is above ground - so if that blows up, I can deal with it.

Considering the radiant heat pipes in the slab haven't blown up in 50yrs and the manifold was copper, coupled with the posts here, I think I will replace the boiler and be comfortable that there is a reasonably high probability the pipes in the slab will last for the next decade.

cpw
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Joined: May 19 2003

Tod,

Did you go with the combined boiler and hot water tank when you installed the Munchkin? I'm considering installing the Munchkin for the same reason you did, reduced carbon foot print as well as likely ever-increasing fossil fuel prices until we go almost all-electric as a country. Most of my use of gas is in providing hot water, so I want to focus on that as well as the radiant heating system.

Chuck

Chuck (West San Jose)

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Joined: May 28 2005

We replaced our vintage 1959 boiler a couple of years ago. It had not quite failed, but was on its last legs and not very efficient. While replacing, our contractor noted that the pipe entering the slab had been accidentally crimped to half the diameter, likely when the house was built. So likely it had never received full flow efficiency even when new.

We have saved at least 20% on our winter gas bills since. As an additional benefit, our heat is now responsive to thermostat changes. We thought previous two-hour lag was inherent to radiant. Turns out, not!

BTW, we went with the Triangle Tube model. No problems so far.

Tod
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Joined: Mar 21 2003

cpw wrote:
Tod,

Did you go with the combined boiler and hot water tank when you installed the Munchkin? I'm considering installing the Munchkin for the same reason you did, reduced carbon foot print as well as likely ever-increasing fossil fuel prices until we go almost all-electric as a country. Most of my use of gas is in providing hot water, so I want to focus on that as well as the radiant heating system.

Chuck

Sorry I missed your query...

We installed a SuperStor "Solar Contender" "indirect" hot water heater. Basically a tank with two heat exchanger pipes in it. On initial install a couple of years ago we hooked both heat exchanger loops to the Munchkin boiler for the domestic hot water. I was disappointed that our summer gas usage did not go down. To me that indicated that the indirect heat system for domestic hot water was no more efficient than the old conventional gas fired hot water heater it replaced.

Last summer we re-plumbed the hot water heater to the way it was intended to use a new solar hot water collection system: One exchanger coil for solar and the other exchanger for the boiler to supplement when solar is insufficient. That dropped the summer gas use to basically zero (our gas clothes dryer is apparently pretty efficient). And so far this winter it looks like the gas use for hot water is down a bit. Hard to exactly say as the day to day cloud cover makes a big difference on the hot water and daily temperature variations affect the usage for space heating.

Side note: We decided on doing solar water before solar electric as the cost per pound of CO2 reduction seemed better. The solar system was installed by a fellow who has done lots of maintenance on older systems but never designed one from scratch. And there are some sizing/design problems that I'll need to rectify this spring. Seems like there are lots of solar electric installers with track records and successful installs but finding a local solar water installer with experience is a bit harder at the moment.

Doing it over, I'd seriously consider using a tankless hot water heater for the domestic and simply feed it from a storage tank that was heated by the solar system. The Munchkin boiler has a pretty high efficiency rating but when heating domestic water the boiler output temperature needs to be pretty high so you don't get the full benefit of the condensing boiler's design. And then you lose a lot of heat in all that coper piping that connects the boiler to the storage tank. Even with those pipe as insulated as possible, there is significant heat loss. I think a tankless water heater with a reasonably good efficiency rating would side step those issues.

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