Minimum temp for Steam boiler water in summer

Dave_61

We have a Burnham boiler around 25-30 yrs old. It is steam, but we have a hot water baseboard loop that a previous owner had installed using condensate (domestic coil was clogged). I was told not to shut off boiler in summer as it could leak due to its age. There is an aquastat that must be keeping at a minimum temperature. I looked at the setting. It is 120 degrees. What is the lowest I could set it? I think it only goes down as low as 100. Thank you.

JUGHNE

Just a question for clarification, how do you heat your domestic water that comes out of the faucets?

Dave_61

We have a GE electric heat pump. Looks like a water heater but takes heat from basement air to heat water.

Jamie Hall

Obviously I can't -- and won't! -- say for sure, but I'd be surprised if letting the boiler just sit, off, for the summer would cause or aggravate a leak if running it on and off (which it does) in the winter time doesn't. If you don't need the water in there hot for some reason, and it sounds as though you don't...

Dave_61

I had read, and was told, that when an older boiler sits cold, seals shrink, and things tend to leak that would normally not when it is kept warm all the time.

RomanP

Dave, at the same time if you heat up your cast iron heat exchanger to 120 degrees, it will start condensing, which will destroy your burner( if it’s a gas boiler), plus your boiler will start getting a build up in between the sections. You are looking at having major issues with that idea ( boiler replacement, potential fire or carbon monoxide poisoning). Another thing to counter that clueless advice is... your boiler isn’t firing up 24/7 across entire heating season? Doesn’t it? I’d say it does go down to ambient temperature few times a day

RomanP

If you are still concerned with potential leak caused by boiler cooling off, which I doubt, set that aquastat to 180! To prevent condensing of non-condensing boiler. Your unit also need call for heat in order to light up that burner. This means, that you will be burning a ton of gas all year round, at the same time your electrical meter will be spinning like crazy, with your AC trying to cool off that same room

Fred

I have a 35 year old Burnham that I leave cold from may until usually October. Being cold won't cause any gaskets to leak because there are no gaskets in that boiler. The sections are tied together with brass push nipples. Any gaskets in the mains or returns (if you have flange unions) do have gaskets between them but they won't leak from being cold either and any heated water, in the boiler that doesn't make steam won't keep those mains/returns warm enough to have any affect on those gaskets. Besides, those pipes, if like mine are 100+ years old and they have not been heated year round, I can assure you.

Yes, at some point the boiler will die, as does just about everything else.

Dave_61

Thanks Fred. Do you fill your boiler with water up to the main to prevent corrosion?

Fred

Dave said:

Thanks Fred. Do you fill your boiler with water up to the main to prevent corrosion?

No, I just add or remove a few inches of water at the end of every season so that the water line is different each summer.

Dave_61

I just looked. I have Burnham V-74T. Any idea if it also has push nipples or gaskets between sections?

Dave_61

RomanP said:

Dave, at the same time if you heat up your cast iron heat exchanger to 120 degrees, it will start condensing, which will destroy your burner( if it’s a gas boiler), plus your boiler will start getting a build up in between the sections. You are looking at having major issues with that idea ( boiler replacement, potential fire or carbon monoxide poisoning). Another thing to counter that clueless advice is... your boiler isn’t firing up 24/7 across entire heating season? Doesn’t it? I’d say it does go down to ambient temperature few times a day

I may have misunderstood the setup. We have 2 thermostats. One for steam heat, and one for the hot water zone. Both are shut off. The aqua stat on the side of the boiler only has settings between 100 and 140. Wonder if it tells pump for hot water zone when to turn on? It was set at 120. Currently, I hear oil burner come on for about 5-10 minutes a few times a day. My ultrasonic oil level gauge says I’m burning about 0.2-0.3 gallons per day.

Fred

All Burnhams have the Brass/metallic push nipples. Weil McLain (or a re-branded Weil McLain) is the only cast iron boiler that I'm aware of that has a composite gasket or rubber o-ring between the sections.

Dave_61

Thanks

RomanP

Dave, do you have heat exchanger installed? Please post pictures of your setup for us to have a better understanding


purchase a strap on thermostat for your hot water piping off your steam boiler. Turn up your thermostat in the room that has hot water radiators/baseboards. When your circulators kick in and burner lights up, Keep checking the temperature on your hot water system piping off the steam boiler until it shuts off. If it reaches 120-140 range, you are in trouble. You need a different aqua stat one that goes to 200 or more. You gotta run your hot water loop 170-180. Otherwise your cast iron sections will start producing condensate, which will cause sections to clog up, your chimney will disintegrate because of moist exhaust, your burner(if it’s gas) will rot out. It’s extremely dangerous situation. Steam boilers aren’t meant to condense

Aquastat shuts the burner off when the water reaches set temp. Should be ~180... this way it doesn’t reach pressure troll setting and start producing steam for the rest of the House. That’s when the call comes from the room with hot water radiators of course

RomanP

It’s hard to use imaginary powers to visualize your setup. Bottom line is you can’t have 120 degree water in your steam boiler when you are running your hot water loop. You will have consequences