Help Me Understand Hot Water Baseboards...

Where is the aquastat set? Aside from the possible flow/air issues you might just not be producing enough available btus. You need to run a high limit of 180* to 195* F or there will not be enough heat available even when you get the flow straightened out.

Don't give up, you will figure this out, maybe a few beers will actually help.

I have monoflow tees in part of my house's baseboard system,, each radiator must be bled separately. If a radiator has air in it it will be air locked..
Radiators or baseboard systems that are in series need bleeding as well, but they usually will allow some water flow.

Take a look at your supply pipe where it supplies the first several radiators.. does the supply pipe have a tee branching off the main [large diameter pipe] then a returning tee to the supply pipe?? There would be a pair of tee's for each radiator..

OR: does your supply pipe go directly to the first radiator, all the water flow through this radiator or baseboard, then go to the next, and next till it is heading back to the boiler via the return piping???

ONe system and a bunch of tees [monoflow tees] the other system has no tees, just pipes, elbows and baseboards.

Greg L

Here's a photo of a monoflo T. Note the ridge, the ring around it. A "normal" tee will not have this ring.

That's a modern looking tee, I'll try to move enough cobwebs out of the way to take a photo of my old cast tees..

Greg L

I have a diversion-tee system in my house as well, it works fine. Each radiator does have its own air bleed valve, the main line is pitched as well.

This website has some good information and diagrams about monoflow tees.

http://www.bellgossett.com/Press/BG-monoflo.asp

Okay guys

After running all around the place and bleeding everything in sequence I acomplished nothing.

Yes it is a monoflow system. It uses the tee's with the ridge in the middle. Goes from one baseboard through supply and return and most of them go onto the next in the sequence, with the exception of a few.

There are three baseboards that are giving me trouble. The rest of the house is fine. When I try to bleed them I get no air. All I get is water, and it is bone cold. If they are air bound I thought I should get air

I cant shut any of them down to pinpoint which one is holding the rest of them up. All three are at the back of the system. I don't want to say the end of the system because the last one in the sequence is working fine. What the hell goes on here?

Im about batty over this thing. Have a notion to give the guy a call and see what he suggests. I don't have the proper terminology to explain it in words on here.... and taking pics may not help because I don't know what to take a picture of.

I think Im just gonna sit down and have that beer that Matthaus talked about.

What does your pressure gauge read on your boiler?

I wonder if the radiators were setup correctly in the first place. How far apart are the tee's (distance between the regular tee and the monoflow on the main line) that feed the cold radiator?

Pressure reads 12 pounds on oil boiler and about 18 on the coal boiler.

I will try to look at the spacing of the tees after supper.

If you know how to adjust the pressure on your pressure reducing valve, you might adjust it up a turn or two and try purging the cold baseboards again. More pressure will cause air that may be trapped somewhere to move along. When your done, set the pressure reducing valve back to where you started.

CoalJockey wrote: Goes from one baseboard through supply and return and most of them go onto the next in the sequence, with the exception of a few.

Where do the "exception" returns go to? I'm wondering if the cold ones are just getting bypassed by flow due to resistance.

Are the cold baseboards all on monoflows or are some also straight thru sections cold also?

CoalJockey wrote: I cant shut any of them down to pinpoint which one is holding the rest of them up. All three are at the back of the system. I don't want to say the end of the system because the last one in the sequence is working fine. What the hell goes on here?

One of my zones is very difficult to bleed using the bleeders. The only way to get a good bleed it is to close off the return and open the purge valve just above. Pretty sure there are some loops between this zone's baseboards that hold air and a "power bleed" is the only way to get it thru.

Mabye replace the bleeder with a 1/8 or 1/4 valve to get a higher volume flow?

Sometimes with an older house that's not level the bleeder may not be at the high point of that branch.If you can try to lift the element in the BB so the bleeder is higher.Monoflo tees don't have much "power" so ANY air will stop the flow.Try to lift up on the bleeder tee and put a little peice of wood or something under it and then bleed that branch.It may help if the presure is at 15 or16 lbs. also.If some of the branches are getting hot that means the monoflo main is air free.The problem seems to be in some branches.
DON