Cold Radiators and boiler short cycles

fabaze12

I just bought a 3 family house in Massachusetts. The radiators running off of 1.5"mains always get hot. The radiators off the 2.5" mains are always cold. The boiler runs, pipes going to second floor get hot, 1.5" main radiators get hot, but the ones off the 2.5" main barely get hot. Thermostat is set at 70F. Whenever we set it at 72F, then the radiators get somewhat hot but not as hot as the radiators off the 1.5" main. Is that normal? Do I just have to run the system at a higher temperature just to heat up the other radiators? Our second floor is vacant and it feels cooler up there. I'm concerned that we'll have to run the system at a higher temperature just to heat that second floor. The third floor is a small apartment and it only has a single radiator.

The other issue we have is how often the boiler runs for. I have noticed at night that the boiler starts and runs for about 6 minutes. Stays off for about 6 minutes and then restarts again for another 6 minutes. The TStat is set to 70F but it never drops below or rises above 70F. Only the radiators off the 1.5" main stay warm. The others remain cold. The TStat is located on a wall between the 2 rooms with the radiators off the 2.5" mains. Any tips and recommendations?

Most of the pipes in the basement arent insulated except for a few small sections that still has asbestos insulation.

Thanks.

acwagner

Is this a one pipe or two pipe system?

I'd start by looking at your main venting. At or near the end of the main should be some vents. See if you can find them and report back what you have. They are likely undersized, nonfunctional, or non-existent, which could be why your system is unbalanced in the heat delivery.

The 6 min on/off cycle for your boiler could be several things. Take a picture of your boiler from different angles and post it here. That will help us focus the discussion.

JUGHNE

If you have a digital tstat it may not be set for steam heating.
In the installer set up programming there may be a function to adjust the cycles per hour. You want 1-2 CPH.
If old school tstat there is a heat anticipation adjust that should be set for "longer".

Jamie Hall

If we assume that this is steam -- then there are several things here. First, as @JUGHNE said make sure the thermostat is set for 1 or 2 cycles per hour if it is one of the newer ones. Then take a look at venting -- whether it's one pipe or two, the mains have to be vented. They may be, but inadequately, or may not be at all. Third, insulate those steam mains. But before you do, make sure that they are pitched properly, with no sags.

fabaze12

Is this a one pipe or two pipe system?

It's a one pipe system, @acwagner

I'd start by looking at your main venting. At or near the end of the main should be some vents. See if you can find them and report back what you have. They are likely undersized, nonfunctional, or non-existent, which could be why your system is unbalanced in the heat delivery.

The 1.5" main has one vent. There's two more near the boiler.





The 6 min on/off cycle for your boiler could be several things. Take a picture of your boiler from different angles and post it here. That will help us focus the discussion.

fabaze12

If you have a digital tstat it may not be set for steam heating.
In the installer set up programming there may be a function to adjust the cycles per hour. You want 1-2 CPH.
If old school tstat there is a heat anticipation adjust that should be set for "longer".

@JUGHNE, here's a picture of the thermostat!

fabaze12

If we assume that this is steam -- then there are several things here. First, as @JUGHNE said make sure the thermostat is set for 1 or 2 cycles per hour if it is one of the newer ones. Then take a look at venting -- whether it's one pipe or two, the mains have to be vented. They may be, but inadequately, or may not be at all. Third, insulate those steam mains. But before you do, make sure that they are pitched properly, with no sags

@Jamie Hall , not sure how to go about changing the cycles on this thermostat.
I sure hope these mains are vented properly. I want to insulate the mains. Ive been looking to get 1" thick insulation from an online retailer. They provided a lot of info so far. In relation to the pitch on these mains, I would have to say they arent 100%. I see some hangers unused, one just off to the side and one that is on but so stretched diagonally across that I dont think that's how it was originally installed.

Canucker

@fabaze12 here is a link to your thermostat manual
https://www.manualslib.com/manual/69948/Honeywell-Pro-Th3110d.html?page=10#manual

Go to pg 8 and look at how to access the heating cycle options. You want to set it to 1 or 2 for your steam system. It comes preset at 5, which will be the number you're likely to see when you first access it

Jamie Hall

Well.... that's a nice old thermostat. It's nowhere near as good as the even older round T87's -- particularly the mercury ones -- and has precious little capability to handle cycling. It is not -- and was never intended to be -- compatible with either steam or hot water heat; it's for forced air. You can either go back to a nice round T87 -- which may take a little fiddling to get the cycles right -- or go to a more advanced Honeywell which has the capability of setting cycles.

fabaze12

Well.... that's a nice old thermostat. It's nowhere near as good as the even older round T87's -- particularly the mercury ones -- and has precious little capability to handle cycling. It is not -- and was never intended to be -- compatible with either steam or hot water heat; it's for forced air. You can either go back to a nice round T87 -- which may take a little fiddling to get the cycles right -- or go to a more advanced Honeywell which has the capability of setting cycles.

@Jamie Hall, that's good to know. I was thinking about replacing it... do you think some of the new ones like The Nest or Ecobee would be a good idea with this boiler? The reason I ask is because I wanted to use a remote temperature sensor to know the ambient temp inside a tenant's unit. Just in case it ever becama an issue... I've also looked into the Honeywell T9 which has optional remote sensors. The Emerson Sensi and Honeywell T5 are the others I've looked at also.

Jamie Hall

I'd take either Honeywell you mention or the Emerson. The Ecobees seem to be relatively trouble free; we've had a lot of trouble with getting Nests to play nice with steam or hot water systems. On the whole I probably go with the T9.

fabaze12

@Canucker, @""Jamie Hall"

I checked the settings on the thermostat.

Here's what I found:

System type: 0 (0 is for gas, oil, electric. 1 is for heat pump.)

Heating cycle: 5 (5 for gas or oil furnaces less than 90% efficiency. 1 is for gravity or steam heat.) Should I change this to 1?

Compressor cycle rate: 3

Temp display: 0 (0 = F)

Compressor protection: 0

Any other changes I should make until I get a new thermostat?

Thanks so far for all the help!

JUGHNE

If you go to 1 now you should see some changes soon.

gfrbrookline

Yes change the heating cycle to 1, that should stop the 6 minute cycles. The

gfrbrookline

The boiler is not being allowed to fire long enough to make enough steam to fill the mains and heat your radiators.

Your main vents are also basically worthless and should be replace with Gorton #2's at a minimum, Barnes and Jones Big Mouth vent's would be better.

Jamie Hall

Yes, if that thermostat can be set for 1 cycle per hour, that's what you want to try.

fabaze12

@Jamie Hall , the Honeywell website has a compatibility guide and it says the T9 isn't compatible with a 2 wire system (R and W). Any ideas on how to make it work in this case?

Jamie Hall

fabaze12 said:

@Jamie Hall , the Honeywell website has a compatibility guide and it says the T9 isn't compatible with a 2 wire system (R and W). Any ideas on how to make it work in this case?

None of them are. They all need power to operate. Most of them can be powered from a local "wall wart", but you can also run a third wire -- the "C" wire -- from your 24 volt transformer. Numerous posts on that.

fabaze12

@gfrbrookline, I checked the main vents. These are vent-rite #75s. Aren't these made for this system?

Are the ones you mentioned just a lot better than these? If thats the case, I'll replace them.

gfrbrookline

The vent-rite 75 has the venting capacity of a radiator vent. You want to vent the mains quickly so you would want a Gorton #2, possibly multiple, or a Barnes and Jones Big Mouth if you don't have issues with water in the system.

fabaze12

@gfrbrookline,

I just ordered a Gorton #2 valve for the main.

I just have one concern... the location of the main vents. They are all located on the return lines. There's on for the 1.5" main side which sits on the return pipe. The other 2 are pretty much right at the boiler on the return pipes also. That's it for main vents. Does that sound about right?

Jamie Hall

That location may or may not be OK. If this is one pipe steam and If these "return" lines are actually continuations of the steam mains themselves, that's fine. However, if this is two pipe steam, or if it is one pipe steam but the returns are separated from the mains by traps or water seals, then it's not fine, except in the special case of two pipe steam systems which use crossover traps on the mains to the dry returns.

So... what is it you have here?

gfrbrookline

It looks to me that you have a one pipe parallel system, which is what I have in my building. You will need a Gorton #2 to replace each of the Vent-rite vents, I see three in the pictures.

fabaze12

@gfrbrookline, the only thing that baffles me is the location of the main vents. They are on pipes that are connected to the lowest spots on these mains. I thought for sure they would be more towards the top to vent out all that cold air in the mains...

Jamie Hall

The vents don't have to be at the high points for steam -- but they do have to be near the ends. Not like water at all.

gfrbrookline

The returns are extensions of your mains until they drop down to wet returns. Having them in the boiler room make it easier to keep and eye on them. Your location is not ideal, in a perfect world they would be 18" before the drop and on 12" nipples.