central heating pump problem

[Dan Robinson]

Steelmasons mentions the pump being undersized and that it depends on the Index circuit resistance, sounds complex, how do I begin to work out something like that, especially if I'm going to add another zone, is it possible to use booster pumps on other zones?

The index circuit is the run from boiler - radiator - boiler that offers the single greatest resistance to flow for the pump.

Modern boilers can often take up most of the pumps capacity just in and of themselves leaving naff all for the heating circuit.

Calculating it is rather tricky when everything is buried. But is the sum of all pipes, valves and fittings in circuit.

Low loss headers and close coupled tees are becoming more common as a result....

Like this one we did a few years ago now....

 

[richard gordon]

Dan,
Thanks, not sure the calculations are for anyone but an experienced heating engineer, hopefully I'll find one for the next stage.

 

[polesapart]

I had a bit of a row with the engineer regarding the placement of the valves as he said it didn't matter.
My feeling is that the gate valve should be fitted on the flow side nearest the direction it is coming from, i.e nearest the pump, is that right or is there some other way of configuring?

It's not the valve placement that matters -with bidirectional TRVs this is optional ( although I prefer TRVs on flow). With some column rads, Acovas being one, the direction of flow through the radiator is critical.

 

[richard gordon]

Thanks polesapart, what determines the direction of flow, is t based on the radiator position in relation to the pump or are there other factors that need to be considered.
I've updated the sketch to show the current position of the valves which are the original wheel valves with traditional lock shilds on the other side all sited on the bottom entry/exit ports, should any of them be changed around?

Heating Plan

• richard gordon
• 28 Mar 2017
• 1