Hydronic loop off steam boiler - Bronze circ pump? Condensate?

takoateli

We have a customer that has a steam boiler with a hydronic loop off the boiler to heat the basement.

The loop is plumbed directly into taps off the boiler. The water in the boiler is extremely rusty and dirty.

We've had to replace the pump (Taco 007) annually like clockwork.

I called Taco, also a manufacture of filters for hydronic heating systems, and Peerless (boiler mfg) and all agreed there's nothing you can do other than just use the best pump possible. The guy at Peerless said to use the bronze version of the Taco 100 which is a lower speed pump which will stir up less of the muck in the boiler, extending the life of the pump.

The guy at Peerless said Dan Holohan who wrote a book which is considered to be the Bible of steam heating, says you should use condensate and a mix of water from the boiler to feed the hydronic loop.

Anyone have any insight or suggestions? Thanks!

Jamie Hall

Using the boiler water directly is fine, though a bronze pump is a good idea. Another good idea is to take the tapping for the feed from about half way up to the normal water level, rather than from low down. There's usually a spot for it. It's also not a bad idea to have a Y strainer in there before the pump.

You can't use condensate as the feed for a hot water circuit -- it's not hot enough. What you can and should do is tie the return from the hot water circuit into the condensate line.

takoateli

Thanks!

EBEBRATT-Ed

@takoateli

No choice except to use a bronze or stainless steel pump. You could partially eliminate the problem if you use a tankless heater or a heat exchanger to feed the hot water loop.

But that brings on other issues an added expansion tank, water feeder and relief valve and maybe another pump

JUGHNE

Which part of the pump gives up the ghost?
The motor or the impeller/pump itself?

Have seen here the recommendation of a 3 piece pump for that application.
Motor is out of the water stream completely and then with a bronze pump there is more longevity.