Where's my expansion tank?

Dyvim

Ok, so it's been determined that I have a gravity HW heating system in my 1929 house. My next question is, where is my expansion tank? I have looked everywhere in the house (basement, garage, all closets, attic, etc.) and there simply isn't one. This isn't something I could easily miss is it?

I found this <a href="http://www.heatinghelp.com/newsletter.cfm?Id=156">article</a> that may explain the situation.

Like in the article, my radiators are cast irons with bottom-to-bottom connections (with maybe 2 exceptions in the entire house), so perhaps the air space in each radiator is forming the expansion tank for the system.

Let me say that the house heats up fine, all the radiators heat up fine, and the pressure on the system is stable. Really the only problems are that it takes a while to get going due to the gravity system, it burns a whole lot of oil, and I have no way of knowing when this 77-year old beast will give up on me (could last another 20+ years or could die in the middle of next winter).

I'm planning to have the boiler replaced, but now I'm wondering whether I should tell them to leave off the circulator pump - I'm worried about how it could mess up the current system which aside from being slow basically works ok. What do you think?

Constantin

Hi Dyvim,

I doubt that you will find a boiler today that has the large tappings and flow characteristics to make a simple gravity system switchout possible. Nor would I really look for one.

The right contractor will be able to match a low-volume circulator to perfectly match the gentle flow that the old gravity system used to generate w/o disrupting anything and obviating the need for massive piping at the boiler. Perhaps a low-power WILO, variable-speed TACO, etc. would do the trick. The power consumption of such a pump would be pretty neglible. If I were in your shoes, I would priortize my spend along the following lines:

1) Insulate and weatherize the house as best as you can. Less heat loss = less need for heat = lower fuel bills. Call up the folk at energystar.gov or the local utility to come in and do a blower-door test, identify cracks, insulation options, etc. then go about getting the place sealed up.

2) Once the house is weatherized, calculate what heating plant you actually need. I would not be surprised if the present boiler will be 4x oversized once you are done insulating. Simply clock the boiler in the middle of a cold winter night and extrapolate what the BTU demand actually is.

3) Lastly, make a decision on what kind of a heating plant you want in the house. Low-mass, condensing, and modulating gas boilers have a proven track record and would work very well with your emitter system. Low-temperature non-condensing oil boilers like the Buderus G215, Burnham MPO, Viessmann Vitola, etc. would also work well. You can even chose among two condensing oil boilers these days, the proven Monitor FCX and the yet-to-be-released pinnacle.

As others have pointed out, you ought to consider all costs when making your decision. For example, a high-efficiency boiler will require a lined chimney. Your existing oil tank and line may need to be replaced due to age and condition. Etc. Also consider the underlying fuel prices in your decision... for example, I have not regretted stayong with oil despite the recent hike in prices, as gas is even more expensive in my area.

Steamhead (in transit)

Read this one too

about a gravity system I found that did not have an expansion tank. It does now!

http://www.heatinghelp.com/newsletter.cfm?Id=151

You say the system pressure is "stable at 15 pounds". Are you certain the gauge isn't stuck?

"Steamhead"

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S Ebels

Ayahh!

Maybe the gauge is stationary but I'm wondering if the system pressure really is? On the other hand, if the rads are two pipe like he says and they don't have air vents on them, each one of them could be an expansion tank. I've seen stanger things...........like no expansion tank at all.

STEVEN MARKS

Check the roof for a vent pipe that could be tied into the boiler system. I have seen and worked on some old gravity systems that only had a pipe from the boiler thru roof.

Weezbo

it may have a tank and the pipe may not come out the roof,the

tank may be hidden and the pipe may return through the house to a basement drain. for example.