Pumping away and high efficiency boilers

Chuckles_4

A Munchkin needs P/S piping. In the boiler loop, it is immaterial whether you "pump away" or not. In the radiator loop(s), you should pump away. (In any case, away means away from the tank, not away from the boiler.)

The boiler loop pump should be one of those specified in the manual, and it won't hurt the Munchkin or lift the relief valve. The specs for this pump have nothing to do with the pump you need on the radiator loop.

Rich Lorimer

Still pump away on a munchkin?

I'm installing my first Munchkin boiler. It's a 399 going in to a church that has radiant in slab from the 60's. I've done quite a few non-condensing boilers and am a big believer in Dan's pumping away philosophy. Now I'm hearing from some that in a high efficiency boiler like a Munchkin or an Ultra that I should pump INTO my boiler? Adequate flow issues?

If I go this route, pumping into, I'm concerned I may over pressurize my boiler. My systems sits at 12 psig static. PRV on the boiler is rated at 30. Using a Grundfos 32-80 (I think those are the right numbers, I'm sure of the 80!) Could I raise the pressure enough to lift my relief while heating and pumping? Also possibly compounding this are my zone circulators on the returns that pump back to my boiler loop and expansion tank.

Any help, thoughts, ideas are appreciated!
Thanks,
Rich Lorimer
Modern Piping
Cedar Rapids, IA

Chuck Shaw_2

Rich

Pumping away refers to the location of the expansion tank. We would prefer you pump into the Munchkin, because of the water pressure switch location. Please refer to your manual, or, if that doesn't answer your questions you are always welcome to call us in the tech support office. We do our best to respond quickly and with as much information as you need. I would like to think we are generally the best source of information on our products.

Chuck Shaw
Technical Support Department
Heat Transfer Products.