Hot Water Baseboard Zone Hot without Calling for Heat

razzor

Hi,

I had a new Biasi boiler put in a year ago, replacing a leaking Burnham V75 or 71. In the last year I have not saved a penny in oil and I have the baseboard zone for my main house getting hot even though the thermostat for that zone isn’t even calling for heat. I don’t think I have zone valves, just circulator pumps. The circulators are on the return side. Does anyone know what could be causing this? I thought I would be saving with oil consumption with this new system. I have enclosed pictures and highlighted the zone that is the issue.

Thanks.

Jamie Hall

First place, on energy saving: unless the new boiler has a significantly higher efficiency than the old one, and -- if it is a modulating boiler -- is run to take advantage of that higher efficiency, there's no reason to suppose you would save any energy: a BTU is a BTU, and it takes a certain number of BTUs to heat the structure. The Biasi boiler is excellent -- but it is not a mod/con, and unless it was tuned nearly perfectly, it isn't enough more efficient than the Burnham it replaced to make a noticeable difference.

Sorry about that. Physics is a rather unforgiving science.

Now on the zones heating when you don't have their specific pumps running -- that's common enough, and is referred to as ghost flow. The best and often only cure is check valves on the zones.

STEVEusaPA

@Jamie Hall He has flow cheks.

Flow check probably needs to be cleaned out or replaced.
Oversized boilers don't save any money, which is what I guess you have with all those zones.
I hope you got a great price on that install, because it looks like a swap out, virtually no new near boiler piping or anything corrected.

OP, what did your contractor say when you posed the questions to them?

Jamie Hall

STEVEusaPA said:

@Jamie Hall He has flow cheks.
OP, what did your contractor say when you posed the questions to them?

Didn't notice that. Sorry.

razzor

Steve, it was a swap out. All I could afford at that time. Are the flow checks the other items in my photo that aren’t the circulators?

STEVEusaPA

Yes, the middle picture. They are all on the supply.
When any other zone is calling, does it feel equally hot on both sides of that flow check? Same for its corresponding circulator.

razzor

Are the flow checks separate or are they part of the Taco circulator?

JUGHNE

Most flow checks have a manual bypass to open them by hand.
Probably the nut on the top. It might be too crusty to move easily.
If the flapper is stuck open you might convince it to close with a rubber hammer.
Or remove the 3/4" square head plug to inspect.
That would require draining the water.

dopey27177

The best way to eliminate water creep is to install check valves after the pumps. The check valves will prevent water from being forced up the zone that is of line.

Jake

razzor

Would it be the flowcheck or the Taco circulator that is allowing the water creep? The circulator is pulling through on the return side. Thanks. 

Jellis

Hey @razzor
the Universal Flow check is what should stop your zone from heating when its not calling.
there is a flapper inside the valve that "swings" closed when the pump shuts off, stopping water from running through the pipes. When the pump kicks on it pulls the flap open and hot water flows through the zone.
Sometimes these checks get stuck open causing the issue you describe.

as described above you may be able to "exercise" the valve by opening and closing it with the nut on top. sometimes a love tap with a mallet is in store to get it to close fully.

If I had done the boiler swap out for you I would have encouraged you to upgrade to new ECM circulators with built in checks and have done away with the old swing checks. those old checks may work fine for another 50 years... or they could start failing one by one... starting now