Help with temperature differences between floors

calmdowneight

I have a 1925 built bungalow 3 story house. Using a 1986 Burnham natural gas boiler with aluminum fin wall mount radiators for heating. This is a hot water system. My issue is temperature variances between the second floor and third floor. On a 32 Fahrenheit degree day with thermostat set to 70 degrees the third level of the home is running about 8 degrees cooler at 62 when the main floor reaches 70. Now, the old house isn’t insulated that well, but the attic does has blown in fiberglass about 5 inches thick. There are no zone valves and the thermostat is on the main floor of the home. This temperature difference use to run only about 4 degrees different with the door closed from the main floor to the upper level and only 2 degrees difference with the stairwell door open. The only change from this season to last is we had to remove the old steel expansion tank due to an air leak and install a new bladder style expansion tank during the heating season last year. This fixed the old issue of having to bleed the top floor rads several times a year. There are only rads on the main level and the top floor of the home, basement is underground and remains 68 degrees year round. There’s about 18 feet from the boiler to the bottom of the top floor radiators. Boiler pressure runs 12 psi cold and about 22 psi at operating temperature before the high heat setting on the Aquastat is reached or the thermostat reaches the 70 degree set point. My circulating pump speed is set in the middle. I’m wondering if the speed needs to be increased to force the hot water to the top floor quicker so that there will be more even heat up there? Thanks

hot_rod

So one thermostat for main and upper level? All one loop I suppose?
You could close down some of the dampers on the main floor fin tube, drive a bit higher temperature up stairs. Basically trying to balance up and main level heat outputs.

No harm in trying speed 3 also. If it gets noisy, like water rushing through the tube, go back to speed two.

If you have flow through the upper fin tube, the new expansion tank should not make a difference.

calmdowneight

Correct, one thermostat and single loop. I didn’t think about closing the damper side some. I know I opened them all wide open a couple of years back. I will try that tomorrow. Speed 3 doesn’t seem too noisy yet. I’m back to a 5 degree difference between floors a couple of hours after the adjustment. Thanks for the advice.

EBEBRATT-Ed

@calmdowneight

Is it possible that when they changed the expansion tank that some air was trapped in the system which would have been pushed upstairs by now? Are all the rads on the top floor as hot as the ones on the lower floor? You could also add some radiation to the top floor. Probably wouldn't take much.

EdTheHeaterMan

EBEBRATT-Ed said:

@calmdowneight

Is it possible that when they changed the expansion tank that some air was trapped in the system which would have been pushed upstairs by now? Are all the rads on the top floor as hot as the ones on the lower floor? You could also add some radiation to the top floor. Probably wouldn't take much.

I was thinking along the same lines. Could someone have adjusted a valve or the aquastat temperature during the expansion tank repair? What is your aquastat temperature setting, and what is the boiler temperature gauge go up to, during a heating cycle.

When something works fine before a repair or service, and it works differently after that repair, then I want to know everything that happened during that repair, even if it has nothing to do with what shows up on the invoice or work order. Valves are often closed for repairs and left closed unintentionally

calmdowneight

The system seems free of air. Only water bleeds off. I have four rooms on that floor and each has a large enough radiator I feel. I expect a few degrees different just because of elevation, t-stat being on the main floor and less efficient insulation up there, but 8 or 9 degrees seems extreme to me.

pecmsg

calmdowneight said:

The only change from this season to last is we had to remove the old steel expansion tank due to an air leak and install a new bladder style expansion tank during the heating season last year. This fixed the old issue of having to bleed the top floor rads several times a year.

Removing that steel tank and replacing it with a bladder tank did require some re-piping work.

Pictures would help.

Jon_blaney

My first reaction is that the heating cycle is to short to satisfy the heat need on the third floor. Maybe something effecting the first floor is causing the issue, like too much radiation, Also are you using thermostat setbacks. This could make the situation worse.

calmdowneight

@EdTheHeaterMan
seems to me that a tech did change aqua stat settings when initially trying to diagnose the expansion tank issue. I will try to get some photos of those settings and the system later on today. Thanks again.

calmdowneight

@Jon_blaney
Im not sure on the set backs. Could be short run times but the main floor always gets to the set temperature before the boiler shuts off. I may have too much radiation on the main level with the damper screws all the way open. Most of the radiators have manual twist open dampers on the covers as well and we’ve always kept those fully open as well.

calmdowneight

@pecmsg
I will take some photos tonight. Thanks

calmdowneight

All valves are opened including the fill valve at the pressure relief valve. Looks to me the aqua stat high setting is at 185. I think this use to be at (180). The low setting I can’t really tell, but I think it was at 160 before the tech changed it. I’m not 100% how to read that one accurately. Photo of the boiler gauge is between heating cycles.

calmdowneight

mattmia2

That's a big tank for fin tube baseboard, did they precharge it properly? Not your problem but the pressure shouldn't be changing that much if it is fin tube. Or do you mean by "aluminum wall mount" that they are convector cabinets?

calmdowneight

@mattmia2
i assume they’re convector cabinets. One radiator is the old cast iron and the rest are wall mounted cabinets with an aluminum radiator similar to an automobile radiator, but about 8” wide, 2” thick and 4-5’ long in a horizontal orientation 8 or so inches above the floor.

mattmia2

Those are convectors. The cabinet needs to be on them for them to heat properly, most of their output is dependent on that chimney effect of the cabinet pulling air through the element.

Is this a monoflow system? Can you show where one of the convectors connects to the main(s)?

EdTheHeaterMan

It appears that your L8148 Aquastat relay is set at 175° to 180°. That is where I would set it. Does the burner operate continusly for the entire call for heat. Most boilers don't. If there is a call for heat and the circulator continues to run but the burner stops. then the Aquastat relay has reached the High Limit setting. This will turn off the burner but allow the circulator to continue to pump the hot water to the radiators. When this happens I want you to look at the temperature gauge and record the temperature.

This will let us know if the high limit is accurate. There may be some over run of 10° to 20° but the burner stops at the 180° setting and the thermometer reads close to 180° then your control is accurate enough.

To be more clear. Set the thermostat 10° above the room temperature. The cold boiler (anything below 120°) will get a call for heat and the pump operates and brings cold water from the radiators back to the boiler. The boiler thermometer may drop in temperature. At the same time the burners start to flame and will start to heat the boiler water. Soon the boiler thermometer will then start to rise slowly. If the call for heat is long enough the boiler thermometer will get to 180° and the burners should stop, but the circulator pump will stay running. This is when I want you to record the boiler thermometer temperature.

The burner stays off and the boiler thermometer increases a little more, then it begins to decrease after a short time. Eventually the temperature drops enough to allow the burner to start up again. Now, the house is too hot by the end of this test, so you can lower the thermostat now.

calmdowneight

@mattmia2
Thanks. They all have cabinets I was just describing the internal heating potion, sorry for the confusion. Each “convector has a water line entering each side of the unit. One line has the bleed valve and the other the damper valve that controls the amount of water coming into it.

mattmia2

How do they connect to the main or mains?

calmdowneight

@mattmia2
They just tap straight off of the main line. I will add a photo of that.

calmdowneight

@edtheheaterman
The boiler / burner runs the entire time heat is called for, until set temp on t-stat is reached or in extreme cases like trying to raise the temp by a large amount the high limit is reached. 

calmdowneight

@edtheheaterman
i haven’t been able to test it as you described, but will try in the next day or two

EdTheHeaterMan

Can I see a picture of the third floor radiator. If it is a convector type, can I see one with the cover off so I can look at the pipe connection from the risers. Looking for the valve and what it might look like.

calmdowneight

calmdowneight

@EdTheHeaterMan
heres a couple of photos. One side bleeder valve and the other has a nut and screw that adjusts water flow.

HomerJSmith

Here's a thought. You have iron piping which has a lot of resistance to flow. Flow is the conveyor belt of heat transfer. Flow is dependent on the pressure that the pump produces and the resistance of the piping. The question is do you have one circuit that serves the main flr and the top flr or are there two circuits one for the main flr and one for the top flr. If you have two circuits that operate simultaneously, then the shorter circuit will get most of the flow and that would be the one closest to the boiler. The cure for that would be balancing valves so that you can equalize the flow in both circuits. Of course, it all depends on how many radiators that you have on each flr.

Increasing the pump speed will increase the flow, but it won't solve the problem of where the water flows. It would increase the temp on the top flr, but also increase the temp on the main flr. If you have two circuits, you need to decrease the flow in the main flr and increase the flow in the top flr given that the radiators are about even on both flrs.

If you have one circuit for both flrs, you are doomed to have a temp imbalanced unless you lessen the radiation on the main flr by closing off some of the radiators or adding more radiators to the top flr. Hope this gives you some ideas.

calmdowneight

@HomerJSmith
it is a single loop without zones. I am going to try to decrease some of the heaters on the main floor to even if some. Especially the room with the thermostat which seems to get hotter than other rooms. I appreciate the info and time!

EdTheHeaterMan

I was thinking of old cast iron gravity fed radiators from the 1940s and before. The ones that were connected to a coal fired boiler. This is not the case. Those convectors were often connected to a one pipe diverter tee system. B&G called there diverter tees, Mono-Flow Tees. That is where you have one pipe going around the basement, the supply and the return of each radiator was connected to that same pipe as illustrated here.

See if your basement piping is set up this way of if there are 2 pipes. All supply connected to one pipe and all the returns connected to another pipe.

calmdowneight

@EdTheHeaterMan
I have one supply line and one return line around the basement. The house had a coal boiler until the NG was put in back in the 80’s. We still have one cast iron radiator, but I assume the rest were replaced with the convectors when the new boiler was installed. Not 100% sure because the house was built in 1925 and we are the third owners. Unfortunately the others are no longer living.

mattmia2

Are both those gate valves open all the way?

EdTheHeaterMan

Another thought I had was one of the old tricks that boiler men used when they installed Gravity systems and the problems that happened when the new heater was equipped with a circulator. Some old timers installed orifices in the top floor radiator valves. This was to balance the gravity system. Once the circulator was added the orifices caused problems that only an experienced boiler man from that time past would know about. Remove the orifices. I don't think this is your problem since you don't have cast iron radiators. But since you mentioned that there may have been cast iron radiators at one time, then perhaps the orifices may still be there. Dan Holohan explains the problem in this podcast https://heatinghelp.com/dead-men-tales/a-dead-men-secret/ .

calmdowneight

@mattmia2
yes, the gate valves are opened fully.

calmdowneight

@EdTheHeaterMan
i will check out that podcast and see if I can locate an orfice in the upstairs units. I’m not 100% Sure on whether originally all of the units were cast iron radiators, but making the assumption based on the fact that we still have one cast iron radiator in the house.

mattmia2

This is part a what changed and part a it wasn't quite right before.

calmdowneight

@mattmia2
I agree. I’m finally getting a day off work to try to decrease flow on some of the main floor units and see if that balances it a little better. Since increasing the circulator speed last week it has been better up there. T-stat on main floor set at 69 degrees, upper level staying about 65 degrees. One of the problems in my rural area is there isn’t a lot of boilers in service and HVAC techs in this area don’t seem to know a lot about them. I’ve had better luck using a local plumber if I can’t fix something myself. I appreciate everyone’s help on here! 

calmdowneight

@EdTheHeaterMan
Today is my first day off work where I could potentially run the test you asked for earlier. Unfortunately, we are dealing with frigid outdoor temps that are only going to get worse like much of the country is having. It’s 9 degrees here at 850 a.m., but was 38 at 1 a.m. Supposed to be below zero this afternoon with high winds, so I’m not sure I will fool around with it today. I’d hate to mess up a good thing at the worst time. I appreciate all of your help and will update ASAP.