Two-pipe direct return heating

pfink

This long run of baseboard has always been a problem. What I had before was a 3ft rad on the second floor. We put a new addition on the second floor and I cut out the 3ft rad and extended that pipe about 15 ft to a 12 ft baseboard and a 2 ft baseboard in another room. It is in the furthest part of the house and by far the longest run.

Two years ago I converted my gas boiler from oil. The boiler before had a circulator also so in my knowledge it was never a gravity system.

Would a stronger circulator be the answer?

pfink

two pipe direct return system balancing

I have a two pipe direct return hot water system with convection type radiators. I recently removed a radiator and replaced it with a long run of baseboard on the second floor. By doing this, I think I have upsetted the balance of my system. I don't get heat in the new baseboard. In the past, I was able to shut down a radiator or two and I was able to get heat upstairs in the baseboard, but for some reason, its not working this year. How can I resolve this situation? And what would have been the correct way to add this baseboard run to my existing system?

Brad White_9

Check a few things....

1) Is the radiation airbound? Can it be purged or better yet, vented?

2) Are there balancing valves on the closer radiators? These could be 'stealing flow' leaving your new radiator with no date for the prom. This may mirror your situation and solution last year. It may also mirror your prom night, I don't know.

3) Is the circulator "pumping away"? This can lead to recurring air problems and turmoil in the Middle East, in that order. Pump away and the first problem will cease.

Unknown

pfink...........

Sounds like your mixing the radiation here, can I assume the system is still gravity? If you had rads-on-feet, and you changed them for a long run of fin-tube, then yes, it`s out of balance. The resistance-to-flow factor is much higher in fin-tube than CI. Did you ever consider adding a circulator to this system?

ScottMP

Brad ???

Liquid lunch again ??

I would make the second floor a seperate zone. There are a mutlitude of reasons why this is the best and easiest solution.

You won't be sorry.

Scott

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Brad White_9

Fair enough

I was going to his question directly but I like your idea better. If Dave's hunch is correct that the radiation types are different, that is another reason. I took them to be copper convectors, same as fin-tube for practical purposes.

Good call Scott!

Brad "Dry Lunch" White

pfink

the rest of the story...

I don't thing the baseboard is air-bound - I am able to bleed out the air out until I get cold water which eventually gets warm. When I close the bleader, the baseboard gets cold.

There are no balancing valves on any radiators, other than valves to turn the radiators on/off.

I have a circulator, no gravity system. I beleive it is pumping on the supply side towards radiators.

The radiator that I replaced is a finned convection type, not copper, but probably black pipe.

Uni R_2

Pressure

Is the system at the same pressure level as it used to be?

pfink

pressure

I can't really tell since the gauge is less than accurate- i am assuming it is. Would increasing the pressure help resolve the problem?

Brad White_9

That was another point

Yes, if this radiator is at the high point, you want to get about 4 psi at the radiator when the pump is off.

Unknown

pfink if............

you have a circulator, and the system is direct return, it sounds like the flow is "short-circuiting" to the rads closest the boiler.

pfink

would increasing the pressure help the problem?

Unknown

Well..........

if your bleeding the rads(on the top floor), getting water and still no heat, then I would say raising the pressure won`t help. It appears you have a flow problem.

pfink

what would be some ways to fix this? In the past, I have gotten heat in this baseboard by shutting off a couple of radiators downstairs, but for some reason I can't get it to work this year? Did I just get lucky in the past?

Unknown

A shot in the dark....................

here, are you sure the circulator is running? What kind is it?, any numbers on it you can tell us?

pfink

it is...

a Taco - model 007-f5. I am assuming it is running, I am getting heat to the rest of the house, including 2 other small radiators on the second floor.

Unknown

Direct return systems,,,,,,,,,,,

are usually associated with a (at one time) gravity system. If it was, and someone added this pump, has it always been a problem since then? If it was piped-up properly you shouldn`t have to "play" with one rad valve to get flow in another.

Al_19

Two-pipe, direct return?

The problem you are having is a classic example of what happens when you remove a convector from a Divertor-Tee (Monoflow, Venturi) system and replace it with a run of baseboard.

Are you sure that you don't have this type of system?

Unknown

pfink

Al brings-up a good point, I never thought of the system maybe being one-pipe, when you say "direct-return", that can entail alot of things, and we are trying to help, but sometimes it`s not easy. Is there a "pro" in your area you could get to come over?

pfink

its very possible, but how can I tell by looking at the tee if they are diverter tees? Its definitely two-pipe though with a supply and return. If I do have these type of tee's, can I just replace them with normal tees?

brucewo1b

Monoflow Tees

have a ring around one of the runs of the tee or arrows saying suppy and return

Unknown

pfink

Yes, you will still have 2 pipes going to the rads, but they will come-off the SAME main. If it`s Mono-Flo, you will only have 1 single main looping around the the system, and a series of tees coming off this to each rad, there are still 2 actual pipes going to, and from, the rad, but as I said, they terminate on 1 single main.

pfink

I definitely have 2 mains looping around the around the system - 1 supply and 1 return - each terminating at the boiler. I also checked the tees and they dont appear like the are Mono-Flo as described above.

brucewo1b

Any way you can get some pics

of the system piping around the boiler and of the tees, is it piped like one of these?
Two Pipe /

pfink

Bruce...

it is piped exacly like the two-pipe direct return diagram on the link.