replacing up feed gravity with new circulator syst

[willy b]

What are the considerations when replacing gravity hot water boiler with new boiler equipped with circulator pump?

[Jim Morrison]

You're going to have to totally rebalance the system.

[willy b]

so what does that entail? repiping the whole house or installing balancing

valves in the existing two circuits?

[kurt]

Sometimes. Sometimes, you don't have to do anything. It's hard to say.

It's not uncommon to reduce radiator size, although it's not always necessary.

Personally, I'd make the switch, turn it on, and see what happened. Then, I'd figure out what to do depending on lots of things.

[willy b]

thanks for the input, thats what I was thinking as well.

[Bill Kibbel]

Is it an open system? If so, it needs to close and a relief valve added.

You'll need flow control valves to prevent gravity flow.

In multi-level buildings, orifice plates were often installed to balance gravity flow between floors. They probably need to be eliminated.

Many contractors install circulator pumps that are way to big when converting, just because the old pipes are big.

You'll need an air separator and a compression tank.

[Rob Amaral]

And don't forget to 'size' the boiler for the distribution load properly.. This is often not done properly.. the result can be a a big problem.. the boiler needs to be large enough to handle the load..

The gravity pipes were often insulated and insulation is often removed. Major heat loss occurs.. Old gravity systems have larger-diameter distribution pipes... compare them to modern hydronic systems that have 3/4" tubes.... Heads up..