Mono flow T baseboard

jmcnulty89

I have a gas boiler 3 years old with a mono flow T system with baseboards one loop does first and second floor everything is feed from the basement I have one baseboard on first floor not getting hot I have bled it multiple times within the last week and it would start to work now I have bleed about a gallon of water and never got hot water and VERY LITTLE air

Ironman

I assume you're asking how to bleed the air out?

Where are you bleeding it from? Can you post some pics of the boiler and its near piping as well as where you're bleeding it?

What's the pressure on the boiler gauge when it's cold? Are there any leaks on the system?

unclejohn

What you are doing is causing flow by letting water out. If air doesn't come out there is none there. You have a flow problem.

Alan (California Radiant) Forbes

Monoflow systems are notoriously difficult to bleed. Increasing the pressure will make the air bubbles smaller and easier to move around. If that doesn't work, add a little Dawn dishwashing liquid to remove surface tension of the air bubbles.

jmcnulty89

I’ve been bleeding it by via the bleeder on the baseboard. There are no leaks If it was a flow problem wouldn’t the baseboards after it have an issue

Dave T_2

@Alan (California Radiant) Forbes Interesting suggestion about adding Dawn. What has been your experience in respect to air bleeding?

Big Ed_4

There are two tees for each section of radiation on the main loop and two risers from the tees to the radiation . The risers should have a constant rise to the air vent and the tees should be spaced on the main the same distance as the radiation .

How is your radiation piped ? Then we can best offer repair suggestions .

jmcnulty89

It is piped as you stated it goes around my whole basement appears to be 1inch and tees off to what appears to be 1/2 inch to baseboards

Big Ed_4

Change the setting of the circulator to hi to increase water volume ..

jmcnulty89

It’s on high I don’t think it’s a pressure or flow problem because further down the line it tees off to an upstairs baseboard and that one works fine

Robert_25

Check the pitch on that baseboard. You might have to shim one end of it to get any entrapped air to go to the vent.

Also - is the vent on your air scoop open? Where is the expansion tank?

Ironman

Get the system hot, then increase the pressure to 25 psi by lifting the bypass lever on the fill valve. Then bleed it some more and let the pressure back down to about 15 psi.

If that doesn't work, find a way to add Dawn and repressurize the boiler.

If that still doesn't work, then there may be a blockage, but don't assume there is until you've tried the above.

As mentioned, Monoflo systems can be extremely difficult to bleed and the fact that a radiator down stream works has no bearing on why another won't.

jmcnulty89

Not quite sure what a air scoop is and what to do with it the expansion tank is right by the boiler if I raise the pressure and bleed it should the bleeding be done at the base board or valve by boiler (don’t know which valves to open and close and where to bleed it that way) I do appreciate the help

Ironman

At the baseboard.

Jamie Hall

"If it was a flow problem wouldn’t the baseboards after it have an issue" No. Actually, perversely, they might even work better.

jmcnulty89

So after reading all the advice I went ahead and bleed every baseboard Just in case there was some air moving around ( got a little air at one other baseboard) checked and opens the vents on the air scoop (got some more air out) then I finally jacked up the pressure to around 25 with boiler running and hot and bleed the problem baseboard till I got hot water and a little more air so it seems to be working right now hopefully it stays that way (fingers crossed) all the advise and help is greatly appreciated very much

Big Ed_4

Normally the problem occurs when someone pulls out the convectors and pipes in baseboard in its place . Screw up number one .

They normally just tie into the existent tees that spaced for smaller convector that throws out three to fours times the amount of BTUs more per foot per baseboard . Not thinking the amount of blockage from furniture placed in front of the baseboard that's to be sutracted. Screw up number two .

If the risers where connected without knowing or care that the bubble has to rise to that tiny bleeder . One of the problems they ran into when decided to replace base board years back . The original installers used bendable tubing for the risers to get that proper air bubble rise .The guys that pulled out the convectors and installed baseboard had to connect or sweat a fitting they had to find a round section . Once tubing is bent it turns oval . The only round pipe to cut into and sweat will be close to the floor boards. Which will not give you enough run to rise to connect to the end of the baseboard 5' down sill to the end of the baseboard even if the floor joists run in your favor . Screw up number three

On As mentioned increase of pressure will compact the bubbles maybe enough to send them up into the baseboard to bleed . A sure fire way is to install a set of purge valves on one of the risers in the basement to force the air out .

Installing baseboard without moving the tees out . Mistake number , Where are we ? number four . Really the biggest mistake was pulling out the convectors for cheap baseboard in the first place.. You will loose some of the flow which would be needed on the coldest day of the year .

I may assuming but I only seen one mono flow system that was originally and correctly installed with baseboard in career with the cave crickets ...

clammy

I think Ed May have hit the nail on it’s head ,on another note what’s up w that flue connection I don’t think that’s kosher it should be smoke pipe not some aluminum flex pipe unless it the liner connected right to the appliance ,always some thing new .as stated convectors w mono flows removed and replaced w baseboard are always a pia , they should have removed the mono flow system completely and replace w a series loop or a split loop makes life much easier . Peace and good luck clammy

jmcnulty89

Im not sure about the flue connection I had a company do a oil to gas conversion 3 years ago they removed everything and put all the new stuff including flue connection and chimney liner so I thought that was good