Room Too Hot

heretic

The intent of your split loop is to make the family room and kitchen output more even. If you had a single loop, the water might be getting cold by the time it got to the second room on the loop.
If I understand the problem, it sounds like you are getting circulation in (part of) a zone that is supposed to be off, so the double loop design itself is probably not the culprit.

John Vence

Room To Hot

System information, 2 story home, 2400 sqft. 100K BTU input hot water baseboard, 4 zones, 2 upstairs, 2 downstairs, upstate NY.

My family room is on the first floor just above the basement where my boiler is. This room is always hot. When one of the rooms on the second floor calls for heat the family room pipes also get hot. My original thought was the zone valve on the family room was stuck open but I had it checked and the service man said it was OK. He said because the pipes are a very short run and the family room is above the boiler the copper pipe will conduct the heat regardless of the zone valve being closed.

The piping for the family room is also setup differently then the rest of the house. The family room and the kitchen next to it have the thermostat between the rooms. The supply line coming out of the boiler gets split sending one to the baseboard in the kitchen and the other supply line to the family room baseboard. At the boiler they get combined back into one return line just before the zone valve. The return lines are also very hot since not much heat is being released in the rooms. For the rest of the house each zone has one loop per zone.

This has been going on since the house was built 15 years ago. It's not a big problem (my wife likes the room hot) but I would like to understand the cause and get it fixed if possible.

So my questions are:

1) What could be causing the family room to heat up when the zone valve is closed? Should I change the piping to have the family room/kitchen flow through a single loop?

2) What temperature should I set the high limit cutoff at? The return pipes on all the zones seem very hot, will lowering the operating temperature help prevent the overheating? The cutoff is at 190 F, the burner comes back on at 170 F, the pressure runs 12psi.

Thanks in advance for your help.

John

John@Reliable

Zone valve

If this has happened since day one,I would bet neither valve was wired wrong or has some solder in the seat causing this zone to heat when any other zone is powered up. To check for this close purge shut-off for that zone,this will not let water enter from supply or return. Now if room is ok I would replace zone valve unit.Hope this helps

Gary Fereday

gravity circulation

BB above the boiler. Supply to it not valved, Return Z valved near boiler. When heat is supplied to the other zones, some hot water flows by gravity to the supply of the BB. In the same time & pipe some is flowing back down to the boiler. This happens a lot with domestic water heaters. I'd place a flow control valve on the supply line. That way the only way water could flow to the BB in question is when the zone valve opens. The other post is valid also. bigugh

Frank_17

too hot

I agree with biguch, but if I undrestand your piping...A split on a zone valve loop. You are getting gravity flow backwards. I.d put in 2 flow checks . one one eihter return line of that loop.before they meet into the common return.

Chauncey

can you draw a diagram of your system

and repost? It removes alot of questions that people have. If all else fails, aluminum foil wrapped around the baseboard elements does wonders to slow down convection currents. C

John Vence

Diagram

Thanks everyone for the help, this is a nice board. What I did last night was I shut down the whole system to get everything cold. This morning I closed the return valve for the family room loop (to check whether the zone valve was stuck open) and turned on the loop for the upstairs bedroom. The pipes for the family room were hot within a few minutes, the return lines are too hot to the touch. The zone valve seems to be working OK and wired OK.

Could the whole system just be running too hot? It seems all the return lines are too hot to the touch. Would lowering the boiler temperature prevent some of the overheating? A neighbor has the same boiler but only 2 zones, his runs around 160F and mine runs around 190F. What should be the normal operating temp?

Rough diagram on the zone loop split:


........./-B-Familyroom---C-supply-A-| |-F-G-return
.........-D-KitchenLoop -E-/

A: is where the 1 1/4" supply line splits into two 3/4" local supply lines.
B&D: are shutoff valves that are always open
C&E: are some sort of a valve, it doesn't have a handle but has a screwdriver slot, I guess this can be adjusted to limit the water flow. I have never adjusted these valves.
F: is a shutoff valve after the two loops are combined.
G: zone valve

The family room loop has 21' baseboard in the heated area and 45' of total pipe run in the basement.

The kitchen loop has 14' baseboard and 110' pipe run in basement.

The other three zones are standard supply > shutoff valve > baseboard > shutoff valve > zone valve > return, but they have 2-3 times the pipe run in the basement to go to the far end of the house and second floor.

Again, Thanks,
John

John Vence

Diagram

Thanks everyone for the help, this is a nice board. What I did last night was I shut down the whole system to get everything cold. This morning I closed the return valve for the family room loop (F in the diagram below) to check whether the zone valve was stuck open and turned on the loop for the upstairs bedroom. The pipes for the family room were hot within a few minutes, the return lines are too hot to the touch. The zone valve seems to be working OK and wired OK. I then tried another experiment by closing valve B and opening valve F and this time the family room piped did not get hot. So I think the problem is caused by the very short family room loop being very close to the supply from the boiler.

To solve this should I eliminate the double loop and make it a single loop going to the kitchen then family room? I could easily eliminate the double loop, the return from the kitchen runs next to the supply to the family room, it will be easy to connect them, then cap the old supply to the family room. What I don't understand is why they were split in the first place. Is this common?

Could the whole system just be running too hot? It seems all the return lines are too hot to the touch. Would lowering the boiler temperature prevent some of the overheating? A neighbor has the same boiler but only 2 zones, his runs around 160F and mine runs around 190F. What should be the normal operating temp?

Rough diagram on the zone loop split:

................|-B-Familyroom---C-|

supply-A-|.................................|-F-G-return

................|-D-KitchenLoop -E-|

A: is where the 1 1/4" supply line splits into two 3/4" local supply lines.

B&D: are shutoff valves that are always open

C&E: are some sort of a valve, it doesn't have a handle but has a screwdriver slot, I guess this can be adjusted to limit the water flow. I have never adjusted these valves. On the valve is says THRIFT on one side and BV 3/4 on the other, is this a butterfly valve?.

F: is a shutoff valve after the two loops are combined, always open.

G: zone valve

The family room loop has 21' baseboard in the heated area and 45' of total pipe run in the basement.

The kitchen loop has 14' baseboard and 110' pipe run in basement.

The other three zones are standard supply > shutoff valve > baseboard > shutoff valve > zone valve > return, but they have 2-3 times the pipe run in the basement to go to the far end of the house and second floor.

Again, Thanks,
John

John Vence

Eliminate the Double Loop?

One more thing, I could easily eliminate the double loop to make this a longer running single loop. The return from the kitchen runs next to the supply to the family room, it will be easy to connect them. What I don't understand is why they were split in the first place. Is this common?

Thanks,
John

Unknown

We see a split loop alot

I think they did that sometimes to save running extra pipes back to the boiler - the only have to run 2 pipes instead of 4 .

Csnow might be right - sounds like you have circulation in a loop thats supposed to be shut . If the zone valve is before the split to the kitchen and family room , and its shut , there shouldnt be any heat going up at all . You said that you had the return valve for the family room shut and the zone valve off , and when you turned on another zone , the family room got hot . Was the kitchen return valve off too ?

Ive heard of ghost flow up one pipe before , but never seen it happen . We dont use many zone valves , but when we do , we install them on the supply side . With a zone valve being on a return , there might be a chance of heat going out of the boiler , and into the pipes , even if the return is valved off . Im not saying thats the cause of the problem , just something to consider . Any way to take some pics of the piping and post it on here ?

The butterfly valve you have are on there to purge out the split loop - the also might be used to balance the heat in the loops . I dont see a major problem making the split loop zone into one zone . We install quite alot of baseboard in Levittown where the 1st floor zone has over 90 feet of radiation on it - and they work fine . If you do try it , dont forget to insulate the pipes going to the baseboard . A better idea would be to make the split loop zone into 2 individual zones . The split is already in the basement . Its just a matter of running the pipes back to the boiler , adding another thermostat , relocating the existing thermostat to a more central location in one of the zoned rooms , and adding another zone valve . Wiring the zone valve might be tricky though . Good luck .

Unknown

Another question or 2

How many circulators are there , and where are they piped in the boiler ?

John Vence

Response and Picture

Again, thanks everyone for the quick replys. To answer some of the questions:

- the zone valve is after the split is joined together

- the zone valves are on the return side

- I have 1 circulator pump located at the bottom of the boiler

I think the problem is the supply pipe is so close to the family room loop, which is a short run, the heat is being transferred without the water circulating. I think a few posts referred to something about that.

I think I will try to make it a single loop for the kitchen/family room. My neighbor's house is the same size as mine but only has 2 zones, upstairs and downstairs and his heats fine.

I've attached a picture that may be of help to the experts.

Thanks,
John