Baseboard Heating System Malfunction

BradHotNCold

We lost electric power for several days in Maine due to recent severe windstorm. When Power was restored, we were advised by our alarm company (it is a second home) that we had no heat. Our property manager called the Company who supplies our oil and he advised us as follows:
“So I spoke with the tech today and he said what happened is when the water pump shut off because of power loss, the draw from the water tank emptied the boiler lines because the pressure tank and boiler are connected. He said a backflow valve is needed between the boiler and the pressure tank to prevent this from happening. Company (name removed) will do the work, and will have it done before you arrive Wednesday. For now he shut the valve off between the two and basically “closed” the loop between the boiler and pressure tank. So heat is back on, we just need the backflow preventer.”
We have had this setup for more than ten years, have had other power outages (it is Maine after all and winters can be tough) but never encountered this problem. I’m not clear if the tech is referring to the heating system pressure tank or the domestic water system pressure tank for our well.
Does this sound like correct solution? Anybody?

Thanks,
Homeowner

JUGHNE

I would say you need the backflow device for the boiler supply.
The tank he refers to would be your domestic well water tank.
The backflow device should be a vented double check. Very common item today for boilers. This would have prevented your grief, by isolating the boiler water from your house water.
Your small boiler water expansion tank should not have suffered.

You were just lucky in the past.

Did you have any chemicals/treatment in the boiler?
If so that may now in your house water supply also by the backflow of boiler water into the system. Whatever was in the boiler has entered your water system. A good flush is recommended even if only plain water was in the boiler. IMO

For the well system to put a suction on your water system the check valve on the pump may be allowing some water back down the well. If the well pump cycles with out any water being used, I would have that checked also.

BradHotNCold

Thanks. We also have a whole house water filter. Would that prevent boiler water back flow into the well? (Feeling really ignorant here and even more appreciative of The Wall!)

JUGHNE

If that is where the boiler water and what ever was remaining in the pump tank when the power went off then it may have back flushed the filter contents down the well. A new filter is in order.

Remember it is just speculation on my part, (1500 miles away) that the water went down the well. But it had to go somewhere??........if you had water turned on somewhere or a "running toilet" in the basement.....someplace lower than the boiler for the water to flow to then it could have gone there.

Not a major worry unless you had some treatment in the boiler. IMO. Someone else here may have a different theory on the water quality and hopefully they will chime in.

Also, if you have an electric water heater it could have been partially syphoned emptied and the elements could have cooked dry. ....not the end of the world.

Jamie Hall

I have exactly the same theory, @JUGHNE -- no surprise there. The entire domestic water supply -- including the well -- should be flushed very thoroughly. A tip for making it so (and it won't hurt anyway): put some chlorine bleach in the well. Shouldn't need that much, but enough so you can smell it. Then flush, starting with whatever faucet or what have is closest to the well, until you can smell chlorine. Shut that off and go to the next one. And so on, until you've run them all.

The chlorine does two things: it disinfects the well, never a bad idea, and it gives you a clear sensory marker that you really have flushed the lines.

Change out the whole house filter (is it one of the cartridge types?) Use a new cartridge before you flush the lines, then another new cartridge when you are done.

Water heater could be a problem, as noted. No big deal.

On where did the water go? Most likely place is back down the well; it is very common for the well check valve to leak a little. But could be anywhere in the house -- as the heating pressure tank would happily push the water out.

And get that back flow preventer on there.

JUGHNE

Another item you may want to consider for the future, if you are gone from home a lot; a low water cut off to shut off the burner if you lose boiler water for whatever reason. This would keep the boiler from dry firing. Lack of heat would set off your low temp house alarm and you could contact the housesitter to check things out.

BradHotNCold

Update with thanks to The Wall!
Backflow preventer installed. Oil company agreed to pay for the part, although they said not covered under our service contract. We have to pay the labor costs.
Oil company technician, who started out as a plumber, also said our well pump installation includes a setup that requires a manual restart after power loss. Without such a control, if we had a water leak in comnjunction with power loss, the pump would come on when power restored and run the well dry.
Question:
Is there any sort of secondary control device that would shut pump off if too much water pumped for too long a period of time?
(I recognise this is not really a heating question per se’.)

BradHotNCold

P.S. Technician verified that we do have a low water cutoff!

JUGHNE

The question still begs; where did the water go?
If you are in the house now, you could shut down the power to the well, be certain you have no water draw and see if the pressure on the water system falls. If so how much and how quickly.

The well may be quite remote from the house and you may not hear or notice that it runs more than it should.

Jamie Hall

There are sensors which can be put down a well. You may or may not really need one -- they aren't all that commonly installed for residential wells.

JUGHNE

When you leave for an extended time you could shut off the water pump. The boiler should not need any additional water.
You could check the boiler pressure before leaving and top off if needed. Then shut off the pump power.

It is possible that there would be a power failure in your absence anyway.

I leave the water supply to my boiler off. I check the pressure before leaving for a long period. Top off if needed. I also have a low water cut off switch.