Home>Discussions>INSULATION & HVAC>oldest known steel pipe radiant slab system? (stil operating!)
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David
oldest known steel pipe radiant slab system? (stil operating!)

Hello forum. Currently debating about whether to replace the BOILER on my radiant slab system from the mid 1950s. First of all, this is nothing like pictures I've seen of the cheap Levittown systems, with the copper pipes lain willy-nilly over bare ground. It's a beautifully engineered 3 zone system with the original circulators and pumps (!) still working fine after over 50 years. The supply pipes are huge, thick black iron. The return pipes curve out of the slab into some kind of collectors. The heating is remarkably even and in the one slab opening I can find, under the bathtub, there is a good layer of gravel under the slab, but, of course, it's not as well insulated as a modern PEX system would be. The house has a very high R value. This weekend I felt a little cold and clicked the thermometer way up and forgot about it for a little over an hour. The house built up so much warmth it stayed at a very warm 70 for over 36 hours with no additional firings! (I usually keep it at 65f because oil is so insanely expensive) The boiler was replaced in the late 70s, only once presumably. I have put a gauge on it, and all last summer, with the supply value closed, it did not drop in pressure. So there is currently no gross leakage from the system.

I read somewhere a while ago of a system from the 30s known to still be working, more recently, I met someone online with a steel system in the DC suburbs from the 40s that is still working...and that in a 2 story house with a poured slab 2nd story...it's amazing settling hadn't busted one of the pipes by now. Anybody else have an old system like this that is still working? I love this form of heat and would like to keep it, even tho the operating costs are high.

Oil dude gave a ballpark estimate of 3800 for a new boiler. For that price there's no way I'm sticking with archaic oil (sorry oil fans). Yeah, I know it has more btus per unit fuel but it's a mess for me because my clay flue liner is flaking from the oil acids and a stainless steel liner is something like 2500 installed. (even more ridiculous than the boiler) So I'd want to get a condensing gas boiler or possibly a tankless gas heater to be vented out a window. (will install a propane tank) It's just insane to have a non-condensing system that you have to keep running just to keep itself warm when the system only has to fire once a day under normal circumstances. The house holds heat so well...165K BTU is WAY overkill. This winter to keep 65F it runs about 40-45 minutes a day max, no matter the weather. (I do not heat one zone though, because it is over the cellar and stays warm anyhow)

FWIW, Oil guy, who seems honest, says I'd be crazy not to just switch to heat pump (from central AC that is totally in the attic, not trivial because I'd at least have to drop some returns) because there's no guarantee the pipes won't fail 2 weeks after buying the new boiler.

JLMCDANIEL
Re: oldest known steel pipe radiant slab system? (stil operating!)

Not sure of your area, but when I switched from oil to propane FA furnace. I installed the furnace and ran a line to the outside of my house. The propane company came and set the tank (a rental), ran the line from the tank to the house, installed a regulator on the snob, hooked up the tank line, and ran a pressure test all for free.
Jack

ed21
Re: oldest known steel pipe radiant slab system? (stil operating!)

Don't go with a heat pump. After the heated slab you won't enjoy the heat pump. The price may be the cheapest though.
I think that in the event of the the radiant pipe failure that adding baseboard heat & using your existing or new boiler makes a lot of sense.
Propane companies in my area, northern Balt. co. will give you a tank with a service agreement.

JacktheShack
Re: oldest known steel pipe radiant slab system? (stil operating!)

Interesting system, interesting post.

You've got a lot of very vintage equipment there, but I think it's costing you a lot of $$$ to hold onto it and not buy into the latest heating equipment, which is twice as efficient as what you got now.

Tremendous improvements in heating equipment efficiency have been made in the past 20 years.

The Burnham boiler is way oversized, & because of its age, there's a good chance it's only 50% efficient.

That means 1/2 the heat is going right up the chimney.

With the sq. footage you've got there, you can heat that with a 70k-80k btu/hr boiler/furnace that will give you 95% AFUE efficiency.

For a rough estimate of the size boiler (and thus, the amount of btu's/hr you need to heat the house), multiply the square footage by 30 or 40.

When you do the heat loss calculations below, they should roughly jibe with the product of your quick multiplication.

You'll have to do a fuel cost comparison between propane and #2 fuel oil.

Propane can be more expensive than oil, depending on where you live.

The FCC sites below will give you the comparative cost of 100,000 btu's of propane as compared to 100,000 btu's of #2.

From your post, I take it natural gas is not available.

The chimney doesn't have to be used with the new propane-fired or oil-fired condensing boilers.

A unit such as a Peerless Pinnacle PO-84A oil-fired or propane-fired condensing boiler emits nothing but a slightly acidic condensate water that flows into the boiler room floor drain.

A new distribution system (the piping/convectors/radiation) would cost a lot for a slab on grade radiant install.

That's why the oil tech probably recommended baseboard.

Another option in a full basement with complete access to the underside of the floor joists, would be a staple-up PEX radiant install.

If you're handy, the baseboard, or staple-up under floor radiant install is often done diy by homeowners.

The summer months are a good time to do this.

In the meantime, beef up the insulation in the exterior walls (R19) and attic (R40).

This will also save $$$ on the AC in the summer.

Do a heat loss calculation (below) to determine how many btu's/hour are bleeding out of the building on a cold day.

Get at least 6 estimates on this job, as the type of heating equipment and prices quoted will vary widely.

http://warmair.net/html/fuel_cost_comparisons.htm
http://hearth.com/articles/47_0_1_0_M7.html
http://www.bgmsupply.com/calculateheatloss.asp
http://www.propane.ca/resources/heatloss.asp
http://www.slantfin.com/heat-loss-software.html
http://www.energystar.gov/ia/products/prod_lists/boilers_prod_list.pdf

bp21901
Re: oldest known steel pipe radiant slab system? (stil operating!)
JLMCDANIEL wrote:

Not sure of your area, but when I switched from oil to propane FA furnace. I installed the furnace and ran a line to the outside of my house. The propane company came and set the tank (a rental), ran the line from the tank to the house, installed a regulator on the snob, hooked up the tank line, and ran a pressure test all for free.
Jack

Jack, Don't know if this still applies, but if you can I would highly recommend buying your own lp tank. This would allow you to shop for propane rather than using the company that is renting you the tank. It makes a big difference in $/gal in our area (last fill up for us was $1/gal delta between suppliers). We paid about $1200 for a 1000 gallon tank about 6 years ago and it paid for itself after the second load. If you buy your tank, save your receipt because one company we sometimes use wants to see our receipt to prove we own the tank and don't rent it.

JLMCDANIEL
Re: oldest known steel pipe radiant slab system? (stil operating!)
bp21901 wrote:

Jack, Don't know if this still applies, but if you can I would highly recommend buying your own lp tank. This would allow you to shop for propane rather than using the company that is renting you the tank. It makes a big difference in $/gal in our area (last fill up for us was $1/gal delta between suppliers). We paid about $1200 for a 1000 gallon tank about 6 years ago and it paid for itself after the second load. If you buy your tank, save your receipt because one company we sometimes use wants to see our receipt to prove we own the tank and don't rent it.

Been looking into that, but I see some problems with owning your own. 1] Liability on rented tanks are covered by supplier. 2]You are responsible for gas loss on owned tank 3] tanks have to be re-certified for use $$$$.
Jack

DonnaD
Re: oldest known steel pipe radiant slab system? (stil operating!)

Oldest?
I also have a slab home, radiant heat and baseboard heat. Original boiler (1952 and still working) with 2 zones and 1 original pump. All good until 2 weeks ago. Large leak under slab, 0 pressure in boiler and told I need a new system. (loved radiant heat but when there is a major leak..but got through 50+ yrs) Hoping it holds out for a few more days until I convert to forced air.
No expertise, just a homeowner with problems and needed to talk.
Hope all works well for you!

David
Re: oldest known steel pipe radiant slab system? (stil operating!)

Thanks for the information Donna. Sorry about your misfortune.

But I don't think your post is going to influence me. I've done some soul searching (and bank account checking LOL) in the past few days. Short of winning the lottery, I'm going to have to go with heat pump and/or propane gas forced air. The simple fact is this system, beautiful as it is, is operating beyond its intended lifespan. Call me skeptical but I don't think today's PEX systems are going to last 50 years.

I find zillow fascinating and sometimes spend hours on it. I was looking at house assessments in an area of very upscale houses that has always been upscale, most in a contemporary style, built from the 40s to the 90s. Average zillow price on this street was about 5 million. Some had been renovated. Only one had radiant floor heating, from the late 60s. (Each house's method confirmed with the state assessment website, that has more detailed info.) It's amazing to me that so few of the very rich either knew about this as a form of heating, or decided they didn't like it. Granted this was somewhere in the East, and I think it was more popular in the West. I specifically searched that neighborhood because it has no houses built before radiant heat would have been a recognized option. To me it is the ultimate luxury! No noise (my cellar has a rebar-enforced poured concrete ceiling), no drafts, no static, it just feels like the inside of your house is time traveling to a warm October day haha! The warm sun shines up from your feet! Wonderful! (Well, if I set it to 70F. I usually keep it at the November setting) I'll miss it but that's life. If there's a bit of saving grace, compared to the last 2 houses I had, this house is much better insulated. So it will retain whatever form of heat I choose. If you win megamillions and build a real mansion...go with the radiant. Not something you are going to find in a Toll McMansion.

(Look at this description of a system even more elaborate than mine. Control system with vacuum tube sockets! Crazy!
http://groups.google.com/group/alt.hvac/browse_thread/thread/d93b4804562089e8/
)

DonnaD
Re: oldest known steel pipe radiant slab system? (stil operating!)

Thanks for replying.......and an update.
Running on one room heated and other zone turned off. Isolated leak to the other zone but no "header" to isolate according to plumber. Now, deciding on forced air ($8,000) or electric baseboard which will need an electric update (included 6,000). Have a new wall unit for AC that cools the entire house.
I wish I was as decisive as you and good luck. I have no idea which would be better since I am paying over 300 a month for gas now. If you're interested, I'll keep you updated.
Still deciding in OHIO.....
If you have any advice, give it.
Thanks

David
Re: oldest known steel pipe radiant slab system? (stil operating!)

Donna. Based on those prices I would go with the forced air option (I assume you mean gas fired). Electric baseboards are going to be incredibly expensive to operate, I think the $2000 difference will be made up in only a couple years. Also I think they are unattractive compared to vents.

I will probably go with a heat pump that can also burn propane. For the typical winter weather we have here in the winter (40s day, 20s night) heat pump is ok. (I don't even like to keep my house very warm) During the really cold periods when heat pumps don't work as well, it can burn propane. As for dropping the returns, someone told me there's a system where they make the wall plenum the return. I plan to research whether that's a good idea or not.

hedgeclippers
Re: oldest known steel pipe radiant slab system? (stil operating!)

DTorrance I have been reading your post with some interest. I too live in Maryland only south of you. I own two houses, One was my grandmothers that I own now and the other one is our home. My grandmothers old house we rent out and we have had to replace three systems in our rental house. For some reason the builder who first owned the house wanted baseboard heat upstairs, a heat pump downstairs and an air handler in the attic. So when those things need replacing it can get kind of expensive. Our tenants are great people but tend to keep the heat up and a door open at times which just taxes the systems so that just makes it necessary to call the repairman in a little bit more often.
I thought I would tell you how much our boiler cost and how much the heat pump was so you can get a better handle on the cost of what you want to put in. The boiler was $8,000.00 and the heat pump was $7,000.00 to replace.
I think you are going in the right direction when you say you are thinking of going the heat pump route. The heat pump would definitely be cheaper to install and I personally think they provide enough warmth as compared to just plain old forced air heat with a furnace which is what we have here at home.
There are a few things to consider though. From what I understood of your post you have an air handler in the attic. Since you do have an air handler in the attic you might want to have your filter in the same area as your central return. That way you will never have to go up in the attic ever again. As for returns with a central return you really don't need any other returns unless you really want them. I myself if I had built the rental house would have put returns in every room and would have run the duct work from a basement furnace to the attic for the cool air/heated air and then return ducts in the basement going to all of the upstairs rooms. It might have been more expensive that way but to me anyway more efficient and it would have been at the maximum only two systems instead of the three it has now.
Another thing too that another poster mentioned already,insulate. The one thing I can't complain about in our rental house is that unlike our own house it is well insulated. At our house we have begun some insulating in our bedrooms and the heating bill certainly is better for it. Also to cut our bills down we replaced our badly warped door with a well insulated door and we have done window replacements in every part of our house except an addition we don't use that often. So all of that helps and as your budget allows I would certainly do as much insulating and replacing of doors and windows as needed.
You mentioned as I remember going with a water heater that would be heated by the boiler water. Since you are going the heat pump route you probably have abandoned that idea and I am glad of that as our plumber said they don't work that well. Instead if you do want to replace your hot water heater I suggest a tankless model that will heat your water as you need it. They are more expensive though so wait until the old water heater dies. We are thinking of doing that ourselves to save on gas costs so if anyone has any comments on those please let me know. Anyway good luck!:)

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