possible leak in indirect coil, can I still use steam boiler for hw?

4tuulikki · May 2021

First time posting. We have steam heat with a SuperStor indirect tank for hot water. I noticed a few weeks ago that the Burnham boiler was acting a bit funny - short cycling because (I think) it was triggering the over pressure cutoff (set to 1). I turned off the steam heat but left the boiler on. I noticed that the water level seemed to go up a bit but then it stabilized, higher than it was before, but was still visible within sight glass. I tried to drain some water from the boiler but drain is apparently clogged. Because the water level stabilized, I thought things were ok, and didn't check on it for a while. Just looked at it yesterday and now the water level is above the sight glass. I turned off the water feed to the hot water tank overnight. No one has been adding extra water and we do not have an automatic feed. Normally during heating season I check it weekly. I don't think the manual feed is leaking but have open/closed it a bit a couple times gently (and quickly), it feels like the the valve is closed. From googling I think there must be a leak in the indirect coil.

Backstory: boiler and SuperStor are about 10 years old. SuperStor loop and valve system (forget correct terms) was messed up shortly after installation, replacement/additional valve jammed open too, so loop has mostly been stuck "open." Hot water can get *very* hot when steam heat is on, we are very careful to avoid scalding. Works normally when steam heat is off.

I know this needs to be seen by a plumber, but I need a bit of time to save up the $$ to pay them. I am keeping the steam heat off until boiler has been fixed by professional.

My questions:
Can I use the hot water in the meantime (would mean turning the water feed back on)?
Is there anything I could do to enable me to be able to use hot water?
What does it mean if water level is too high but boiler is not being used for steam?
Is this unsafe?
Are there other places I could drain water from, or any suggestions to get drain unclogged?
Thank you very much for your help, it is greatly appreciated.

Jamie Hall · May 2021

A leak from an indirect to a steam boiler is hardly u unheard of. Rather common in fact in older units.

Having turned off the water to the indirect (and if the valve to which you refer is a mixing valve which it sounds like, the cold water inlet to that, too), does the boiler water level continue to rise? That would be the best clue.

Can you use the boiler for hot water when it is overfilled? Yes. But be sure that the aquastat controlling it doesn't let it steam, and make sure that you don't accidentally turn the thermostat up and call for steam.

Better yet, figure out how to lower the water level in the boiler. I'm not really surprised that the actual drain for the boiler is plugged. you could try opening it and then using a really stiff wire seeing if you can poke back through it to dislodge the crud which is plugging it. That sometimes works well. There may also be drains on the sight glass which you could use, and many low water cutoffs have a blowdown valve which you certainly could use (but you are likely aware of that -- as it should be blown down during the heating season from time to time anyway...). There may also be a drain valve somewhere on a cold return, if there is one.

4tuulikki · May 2021

Thank you so much! I couldn't get the drain unclogged, but I was able to find the drain valve on the cold return and used that to drain some of the water out of the boiler. It apparently was filled just to the top of the sight glass. Afterwards I turned the water feed to the SuperStor back on. Boiler water level didn't change last night but this morning it's up maybe a gallon or two. I will keep a close eye on levels, but it is very helpful to know that as long as I don't turn on the steam heat, it should be ok (or at least ok-ish).

mattmia2 · May 2021

Turn off and depruesurize the dhw over night and make sure it doesn't happen to conform it is the tank and not something like the feed valve for the boiler not shutting off completely or someplace else water is being trapped and released on the boiler side.

Don't keep doing the drain down of the boiler for an extended period. That fresh water will eventually destroy your boiler.

JUGHNE · May 2021

To unclog the boiler drain, sometimes back flushing it with house water pressure will dislodge the gunk.

Do this only if your boiler is off and cool.

I have used a water supply from the water heater drain or the washer connection. Use a double female ended hose....you can use a washer supply hose for this.
Pressurize the hose connected to the boiler drain and then open the boiler drain to get the house pressure to back flow into the boiler. Back and forth a few times and then the boiler will drain.

In the future you should remove the worthless factory boiler drain and replace with a full flow ball valve.

If the boiler overfills only with the indirect cold supply on then the tank coil is leaking and that means a new indirect tank....not a cheap fix.

4tuulikki · May 2021

Thanks everyone for your help. Boiler water level has *not* continued to rise, just goes up and down a bit I think due to expansion/contraction as boiler warms or cools. So maybe it was the boiler feed after all, and I fixed it. But I'm still going to keep an eye on it, and also get boiler seen asap, definitely before next heating season, it's well overdue.

possible leak in indirect coil, can I still use steam boiler for hw?

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