Weird \"Pumping Away\" Problem

Mike T., Swampeast MO

Am installing a Vitodens into a gravity conversion system. Retaining the existing simple boiler (a Weil-McLain CGM) and circulator (B&G 100) for backup. Existing system pumps away with the PLAIN compression tank (with Air-Trol fitting) connected to the built-in air separator in the W/M.

Valves allow me to easily isolate either one or the other boiler, both in supply and return.

Am using the high flow ability of the B&G and the built-in air separator for the initial air purge.

Now my problem.

If I close both valves leading to the W/M, the compression tank is isolated from the Vitodens. I've installed a separate vented air remover in the supply line of the Vitodens.

So, I made a second connection to the compression tank that comes into a tee in the water fill pipe that connects into the supply connection of the Vitodens to the system.

Impossible to get more than a pound or so of differential pressure in this system.

Have I done something stupid?

Do you need a drawing? (Photo won't really show.)

Suggestions for an alternate connection to the compression tank for the Vitodens portion?

Carl PE_2

hmm

A sketch would be good.

What happens if you only close one valve on the non-firing boiler? perferably the one nearest the check valve..

I assume you've got check valves on both pumps.. so why valve it off at all?

I think it'd be best if you installed one air separator in the common boiler header, and hooked up the compression tank there. Or, I suppose you could tee the tank into the vito air separator.

I think we need some more info.

Carl

Bob Depew

need more info but sounds like you need to change system to primary secondary pumping. old boiler and new one on gravity systems need to be installed that way to contol and operate better. if all the flow is going through boiler you are not installed to boiler instuctions. Cgm should be installed only p&s to keep from condensating. need to go back and repipe properly. need to invest in dan's books or get a contractor to do it right

Mike T., Swampeast MO

Primary secondary NOT required and NOT desired. TRVs on all of the radiators and flow is very much within the ability of the built-in circulator of the Vitodens.

Took a photo from another angle and am working on labeling it.

Mike T., Swampeast MO

Looked, and looked and looked again, and the Vitodens installation examples clearly show (and say to make note of) the compression tank location. In the boiler supply at the fill connection. Exactly where I've placed it when the Vitodens is in operation. Seems to violate "pumping away" but it's what they say...