Gravity Hot Water

jim sokolovic

Could there be leak in the inner part of the heat exchanger that drips into the combustion area and gets evaporated by the flame, therefore not pooling outside the boiler?

Mike Strong

Gravity Hot Water

I have a customer with a gravity hot water system. It had always worked great (the house has been in the family forever). It was serviced annualy and appears to have been spit shined! Over the last 3 years or so, he has had to add water to the system. In this particular system, he has to add approximately 1 gallon of water to return the boiler to approx. 12 psi. This has to be done on a monthly basis. We can find no evidence of leaking water anywhere in the house. Any ideas as to where this water may be going?

Wayco Wayne

The last

gravity system I worked on had a tank upstairs that vented out onto the roof instead of an expansion tank. If your boler has one of these you could be getting evaporation through the roof. WW

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Mike Strong

This particular tank vents to the basement, but I think that the evaporation would have been taking place all along and not just the last 3 years

Mike T., Swampeast MO

Still under gravity?

The water MUST be going somewhere...

If it's not a super-slow leak in the boiler I'd suggest that you have the homeowners do a MINUTE inspection for mineral deposits--particularly at rad connections and between rad sections.

Believe it or not Fuller Brush Company still makes a very good radiator cleaning brush.

Mike Strong

We have looked high and low on the entire system for leaks. Nothing is obvious at this point. The heat exchanger is spotless (believe it or not). You could almost eat out of there, although I would not recommend it. After all, we know what goes on in there. There are no visible signs of water leakage anywhere. Now that I sit here and think about it, if the piping leading to the exp. tank is mostly plugged, and he doesn't vent the radiators properly, by manually filling the boiler, he would therefore compress the unvented air which would show "pressure". When the air works its way through the mostly plugged exp. tank piping, the "pressure" would bleed off and return the gage to "0" making one think that there is a leak. Any thoughts??

Unknown

Strong possibility

The other factor is dissolved gasses in the water coming out as the water is heated, then being removed by an air vent. Not all gasses in the water are air, but they act like air to the air eliminator.

Noel

Al Letellier

leaking gravity system

Mike, could you have a leak in the boiler down low, behind or under the combustion chamber? A leak here would be absorbed by the block or filler materials and vaporized when the unit fires
What kind of boiler is it and what does it have for a fire chamber?

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Guy_5

Leaking boiler

If the boiler were leaking into the combustion area it would also be steam cleaning the boiler, therefore giving it that "spring fresh" look. Many leaks in that area that I have come across only appear when the unit is running. The increased pressure from the heat, combined with the metal's new ability to expand (due to a crack) allow the leak to present itself. A good sign of this is an abnormally large exhaust plume out the flue.

tim smith_2

loss of pressure on gravity

I have had many old mansions that have started to lose pressure, I would guess there are some underground returns in basement due to it being gravity with probably some basement rads. You might need to get a good leak detection company in to sound out where the leak is. We have dug many a holes in such places to repair undergrounds. I hope this is not the case, but good chance at the loss rate with no visible signs of water.