Furthest radiators slow to heat

joco

Hoping someone can point me in the right direction. 2 radiators in my 2nd floor bedroom will only heat about 2 fins before the thermostat shuts it off. The boiler is on the opposite side of the house, it’s about a 100’ long run.

To get heat to these rads I set the thermostat to 1.5’ differential so I have a longer burn. 

I have a 2 pipe system, replaced 90% of the traps over the last 2 years (including these), replaced wet returns, vented the mains. I have a vapor stat, I think it’s at 4oz. In 3 years we’ve lived here I’ve never seen the needle move. 

One guy told us the rads don’t heat because boiler is undersized and it’s piped ****. IIRC it’s 10% undersized, which doesn’t sound like much to me but what do I know. We have a 400kbtu and he was recommending 425k.

Replacing the traps helped a lot with banging, but I still have some noise. 

nicholas bonham-carter

Are the rooms getting warm? In early winter, with moderate cold, the system may not need to fill all the radiator.
For comfort.
Are there any crossover traps in this system? They are critical to proper function of some two-pipe systems. You need 1005 of the traps working to get the air out.—NBC

BobC

Thats a lot of pipe that has to get up to steam temperature - is that main insulated? The radiator feeds off that main sb insulated as far as you can reach as well.

Bob

KC_Jones

How much main venting? For 100' main you will need, at least, 3-4 Gorton #2 vents, maybe as many as 5. Vent location also depends on system design. If the main ends with a wet return you will also need vents on the dry return for the radiators. If you have the crossover trap then the vents will be on the dry return only. Also, the above recommendation is for the main only, if you have vents on the dry return, you may need at least 1 more Gorton. Others more well versed in 2 pipe may be able to comment further on that.

I don't believe the boiler is undersized by the amount suggested. That's only a 6% difference and can't be enough change to create the issue you have IMHO. The boiler piping could be causing issues, we need to see pictures of that to comment. That would help a lot.

joco

Are the rooms getting warm? In early winter, with moderate cold, the system may not need to fill all the radiator.
For comfort.
Are there any crossover traps in this system? They are critical to proper function of some two-pipe systems. You need 1005 of the traps working to get the air out

No the room is not heating well. Last night after a burn the thermostat was at 72 and that room was at 66. There are some insulation and draft issues, but those radiators are not helping much. The rest of the house heats really well other than some light banging.

There are no crossover traps.

How much main venting? For 100' main you will need, at least, 3-4 Gorton #2 vents, maybe as many as 5. Vent location also depends on system design. If the main ends with a wet return you will also need vents on the dry return for the radiators. If you have the crossover trap then the vents will be on the dry return only. Also, the above recommendation is for the main only, if you have vents on the dry return, you may need at least 1 more Gorton. Others more well versed in 2 pipe may be able to comment further on that.

I count 9 big mouth BJ vents in different places. They were put in at the same time our wet returns were replaced. Someone I found on this site did the work, same person who suggested boiler is undersized. No offense if he reads this, just looking for other possibilities than a new boiler

This was a Haines vacuum system -- we took it out of vacuum when installing the vents.

Here are some photos, let me know if anything else would help.

dopey27177

Steam piping in vacuum systems generally is a bit smaller than steam piping in a just plain steam systems.
so if there is a problem with heating it is to the entire structure.

If this was a two pipe vacuum system there is or was no need to put vent valves on the system.

Because you no longer heat at a vacuum the operating steam pressure needs to increased to at least 1 psi off and 12 psi on. You may have to increase the pressure settings.

Because you are a 2 pipe system you may and I say may have to install a small condensate pump and remove those vent valves.


Jake

joco

dopey27177 said:

Steam piping in vacuum systems generally is a bit smaller than steam piping in a just plain steam systems.
so if there is a problem with heating it is to the entire structure.

If this was a two pipe vacuum system there is or was no need to put vent valves on the system.

Because you no longer heat at a vacuum the operating steam pressure needs to increased to at least 1 psi off and 12 psi on. You may have to increase the pressure settings.

Because you are a 2 pipe system you may and I say may have to install a small condensate pump and remove those vent valves.


Jake

So here's the thing about pressure -- I've never seen any on the vaporstat, even after running it for an hour coming home from vacation.

All the rads heat up fully except for this one room. The bedroom next to it heats slow also, but at least the rads will get going. I was told we could always return it to vacuum by replacing the big mouths with vacuum vents.

You can see how this system was set up here: https://books.google.com/books/content?id=O9JBAQAAMAAJ&pg=RA1-PA925&img=1&zoom=3&hl=en&bul=1&sig=ACfU3U16U8ssAycU74I2SCHSsUcyxnToUQ&ci=109,86,774,1050&edge=0

Jamie Hall

There are a number of things about this system which I really don't like much, looking at it, but they are mostly minor, and if it is working satisfactorily I'd leave it alone.

Howeve.

Have you really gone back to the beginning on those two radiators? We know the rest of the system is heating well and the pressure never rises, so we know it's adequately vented (in fact, that's one of my problems with it -- it's wildly overvented). We know the boiler makes enough steam. I presume the mains are adequately vented, considering the shotgun approach to vents everywhere. But... those two radiators don't heat. OK, for a radiator to heat the steam has to be able to get to it and the air and condensate have to be able to get out. So -- Find the nearest steam main which gets steam. Trace the runout to each radiator in question. Does it get hot for its full length? If not, where does it stop? Find out why the steam stops there and fix the problem. Now you have steam to the radiator valve. Is that radiator valve open? It wouldn't be the first time. Now go to the outlet. Is there a trap there? Is it known to be working? Trace the return line. Does it drain freely to the nearest return which drains a known good radiator? Is the return line or the one it drains into steam hot? It shouldn't be.

All this takes longer to write than to do. But stop chasing phantoms in the basement, or undersized boilers, or extra vents in the corners, or questions about Haines vacuum systems, or whatever, and find out why the steam doesn't get to those radiators.

dopey27177

Made a TYPE O


Where it says 12 psi on it should be 1/2 psi on

Jake

cross_skier

I had 2 second floor radiators that did not heat consistently and of course had cold risers.  I added vents to the top of the  risers with little street elbows and the problem was solved.

I have never heard of too much venting on mains but I'm no expert in 2 pipe.  My longest main is 55', I added a main vent in the middle of it on a pipe tapped into the main.  I also have antlers at the ends of all 3 mains.

joco

Jamie Hall said:

There are a number of things about this system which I really don't like much, looking at it, but they are mostly minor, and if it is working satisfactorily I'd leave it alone.

Howeve.

Have you really gone back to the beginning on those two radiators? We know the rest of the system is heating well and the pressure never rises, so we know it's adequately vented (in fact, that's one of my problems with it -- it's wildly overvented). We know the boiler makes enough steam. I presume the mains are adequately vented, considering the shotgun approach to vents everywhere. But... those two radiators don't heat. OK, for a radiator to heat the steam has to be able to get to it and the air and condensate have to be able to get out. So -- Find the nearest steam main which gets steam. Trace the runout to each radiator in question. Does it get hot for its full length? If not, where does it stop? Find out why the steam stops there and fix the problem. Now you have steam to the radiator valve. Is that radiator valve open? It wouldn't be the first time. Now go to the outlet. Is there a trap there? Is it known to be working? Trace the return line. Does it drain freely to the nearest return which drains a known good radiator? Is the return line or the one it drains into steam hot? It shouldn't be.

All this takes longer to write than to do. But stop chasing phantoms in the basement, or undersized boilers, or extra vents in the corners, or questions about Haines vacuum systems, or whatever, and find out why the steam doesn't get to those radiators.

Thanks for the reply. I don't see anything obvious. But I'm just a homeowner who's read Dan's book. I think both of the radiators are fed by the same riser, which knocks when the system starts up. There seems to be proper slope for the return. They are going to be really f'n hard to access so I hope that's not the issue.

The traps are new on the radiators. The valve is a TRV but I removed the thermostat dial because I was told they would cause trouble, so it's just the little metal pin for now. The pin moves up and down so it's not stuck. The radiator pitch is wrong, but pretty much none of my radiators are sloped correct and the others heat OK. I'm wondering if the valves could be clogged.

Also I checked the vents again, it is 3 big mouths on ends of each of two mains, and 2 big mouths on each of 2 dry returns.

dopey27177 said:

Made a TYPE O


Where it says 12 psi on it should be 1/2 psi on

Jake

1/2 or 12, still will never see any pressure

cross_skier said:

I had 2 second floor radiators that did not heat consistently and of course had cold risers.  I added vents to the top of the  risers with little street elbows and the problem was solved.

I have never heard of too much venting on mains but I'm no expert in 2 pipe.  My longest main is 55', I added a main vent in the middle of it on a pipe tapped into the main.  I also have antlers at the ends of all 3 mains.

thanks I am getting close to trying this...

Jamie Hall

If the riser knocks when the system starts up, is it a water hammer or expansion? if it's a water hammer, somewhere in that riser there may be a bit of pipe -- needn't be long -- which is horizontal or nearly so, and it may not have enough pitch. That can be a real ause of slow or even no heat.

Jon_blaney

How about some pictures of these problem radiators? Also some of the working ones.

dopey27177

try setting the t stat at 85 degrees for a boiler longer run time'
If the pressure increases to 1psi off the problem is T stat in wrong place in the house.

jake

joco

Jamie Hall said:

If the riser knocks when the system starts up, is it a water hammer or expansion? if it's a water hammer, somewhere in that riser there may be a bit of pipe -- needn't be long -- which is horizontal or nearly so, and it may not have enough pitch. That can be a real ause of slow or even no heat.

I came back from vacation which gave me the chance to run the boiler for a couple hours. Both of these radiators did eventually heat up all the way across, but the supply pipe on each gurgles pretty loud. So it makes me think there's water trapped somewhere. I'm going to try raising the radiators and see if that gives me enough pitch. Is there anything else I can try short of opening the floor/walls?

Hap_Hazzard

What size is the pipe supplying these radiators?

What is the EDR of these radiators?

If you don't know the EDR, can you give us the details, i.e. height, width, depth, number of tubes and sections, and possibly a picture or two?

ethicalpaul

joco said:

I came back from vacation which gave me the chance to run the boiler for a couple hours. Both of these radiators did eventually heat up all the way across, but the supply pipe on each gurgles pretty loud. So it makes me think there's water trapped somewhere. I'm going to try raising the radiators and see if that gives me enough pitch. Is there anything else I can try short of opening the floor/walls?

That was a useful finding. There's definitely water in the supply (either from an unintentional water trap probably due to house settling or from carryover from the boiler). Venting won't help you.

I keep pasting this all over the place, but here was my adventure with that problem: https://forum.heatinghelp.com/discussion/167233/fixing-pitch-issues-in-old-house

joco

Hap_Hazzard said:

What size is the pipe supplying these radiators?

What is the EDR of these radiators?

If you don't know the EDR, can you give us the details, i.e. height, width, depth, number of tubes and sections, and possibly a picture or two?

I've attached a photo of the 2 radiators as well as the riser from the basement. I think both radiators are fed from the same riser.



As you can see it's a real pain to get at the riser pipe, it's run off the supply to indirect radiators, and the pipe is squeezed behind the ducts. There is some banging that comes from it on startup.

Hap_Hazzard

If both radiators are fed from a bullhead tee, that could be a problem, because it's impossible to pitch the two branches in different directions, so it would be helpful to see exactly how they did it. If you can't get at the pipes from below, you might be able to feed a flexible borescope down from above, but you'd have to take the traps off.

neilc

#pigtail ?

all your gages and trols are above a single steel pigtail,
has that been checked for cleaned and clear back into the boiler ?
maybe you're not seeing the pressure you may have(?)

the 2 traps,
sometimes they freeze shut,
have you opened their caps, and jossled them?
and then they work again

joco

Hap_Hazzard said:

If both radiators are fed from a bullhead tee, that could be a problem, because it's impossible to pitch the two branches in different directions, so it would be helpful to see exactly how they did it. If you can't get at the pipes from below, you might be able to feed a flexible borescope down from above, but you'd have to take the traps off.

Thank you the borescope is a good idea. I was able to find the riser + return for the other radiator. I’m going to try to raise the radiators a bit over the weekend and if that doesn’t work I’ll put a camera in there to see where the water is pooling. 

neilc said:

#pigtail ? all your gages and trols are above a single steel pigtail, has that been checked for cleaned and clear back into the boiler ? maybe you're not seeing the pressure you may have(?) the 2 traps, sometimes they freeze shut, have you opened their caps, and jossled them? and then they work again

The pigtails are clean. I did see pressure the other night after about 90 minutes. The traps are brand new this year, and the radiators do eventually heat, just very very slow. 

neilc

how do these 2 rads get their air to venting ?

JUGHNE

Are the indirect coils still connected?
If so can you isolate them, they could be stealing steam from the risers.

If that improves things perhaps you could repipe to the indirects if you need them.

I had a job where there were 2 large fan coils on a gym stage, the stage was walled off to be a separate room, the steam still flowed thru the coils. The room got so hot that AC was added to it. I shut the valves off and no longer needed the AC.
Just a for instance on how some simple things are overlooked.