Adding loop to Boiler

MatthewKlein

Hello,
I am in the process of adding a loop of cast iron radiators to the existing 1959 boiler system with plain steel compression tank. Originally fire station. System currently has 2 loops - one baseboard for meeting room and hanging radiator w/fan in truck bay

1. New pipe is pressurized to 30psi and after fixing leaks sill looses 3psi over 9hrs. Guessing need to continue with the soapy water and find the leaks.

2. Plan to add Caleffi air separator to hot side of new loop before circulator and Dirtmag on return. Is this a good idea and proper locations? Right now system has 5 automatic air bleeds in the existing loops. Existing circulators are on boiler return side.

3. Plan to add valve before air separator to purge air during boiler fill.

4. Plan to add wide spot in new loop piping return with fill and drain to add chemical treatments. Is this a good idea?

5. Nervous to drain and fill boiler.
- Compression tank has B&G Airtrol tank fitting.
- Isolate existing loops.
- drain boiler and compression tank.
- Close valve to compression tank.
- Fill boiler.
- Fill new cast radiator loop
- Open valve to compression tank, open fitting on Airtrol, when Airtrol weeps water close fitting?

Thanks, Matt

nicholas bonham-carter

I think that the air removal should be handled solely by the compression tank.
How are the rads piped, parallel return?—NBC

Jamie Hall

If the Airtrol is still working properly -- which will be clear if the system maintains a reasonably constant -- say plus or minus 3 or 4 pounds -- do NOT add an air separator. Of any kind. Anywhere. It will defeat the Airtrol and the compression tank will waterlog -- which you really don't want.

It's OK to have a valve which you can release air from -- manually. But I doubt very much that you'll need it.

MatthewKlein

nicholas bonham-carter said:

I think that the air removal should be handled solely by the compression tank.
How are the rads piped, parallel return?—NBC

Reverse return

MatthewKlein

Jamie Hall said:

If the Airtrol is still working properly -- which will be clear if the system maintains a reasonably constant -- say plus or minus 3 or 4 pounds -- do NOT add an air separator. Of any kind. Anywhere. It will defeat the Airtrol and the compression tank will waterlog -- which you really don't want.

It's OK to have a valve which you can release air from -- manually. But I doubt very much that you'll need it.

Have not paid close attention to the pressure but do not think it fluctuates.

Thank you for the advice.

Do I drain and fill the compression tank when draining and filling the boiler?

EBEBRATT-Ed

First off is the boiler sized right for the existing load on the boiler plus what is being added??

Jamie Hall

You can drain the compression tank, that's fine. It will happily refill itself to the correct level, always assuming that the Airtrol is working -- and it sounds like it is.

MatthewKlein

nicholas bonham-carter said:

I think that the air removal should be handled solely by the compression tank.
How are the rads piped, parallel return?—NBC

Reverse return

EBEBRATT-Ed said:

First off is the boiler sized right for the existing load on the boiler plus what is being added??

Was built without insulation. Also think boiler was oversize even then. Insulated in the 70's I think. Should be enough for the addition.
600,000 input 480,000 output. Heat loss has been calculated for existing Zone1 210,000 Zone2 80,000 New Zone 55,000