Positioning of pump (orientation)

[peweuk]

IS it possible the pipework has been piped Flow-Flow by mistake or vise-versa?

Not sure what you mean by that Can you elaborate?

I simply put a 'T' in the existing flow and return pipes (just after the pump) and ran these through the loft to the extension where I then 'T'd each of the new rads off in turn.

If I 'drain' the system at the end of the new flow pipe (with pump off) the hot water flows through, but there is no circulation when the pump is running.

 

[looneyfitter]

Dont mean to sound contarasending mate but have you defo teed into the return?

Also took a pipe from each of the pipes to each rad?

Could well be air locked on the new return. Try linking the flow and return together at the furthest point with a gate valve in the middle (like a by-pass)

http://www.miketheboilerman.com/pipeworklayouts.htm

similar to the 1st diagram mate?

 

[peweuk]

but have you defo teed into the return?

Yes - definitely teed into the return

Try linking the flow and return together at the furthest point with a gate valve in the middle (like a by-pass)

Done that - and have installed various 'bleed' points along the pipework to ensure flow all the way round when filling.

 

[peweuk]

It works!!

This morning before doing any other alterations I started up the boiler again, and now heat is flowing through the whole system.

I had done nothing to the pipework or pump, so go figure

A bit bizarre, but all I can think off is that it could have been a small airlock which allowed a small amount of water past when filling but offered just enough resistance to inhibit the circulation and this maybe 'settled' overnight.

 

[looneyfitter]

Fantastic matey... Must have just been an airlock

 

[peweuk]

Thanks. Now that frustration is over, next step is the laborious task of 'balancing' the system

Then I have to consider the best way (if it can be done successfully) of adding an air source heat pump as a 'pre-heater' for the oil boiler

 

[looneyfitter]

Why a pre-heat mate? How big is the house? You could always use a thermal store.

 

[peweuk]

Why a pre-heat mate? How big is the house? You could always use a thermal store.

I looked at thermal stores and on discussion with suppliers (such as Gledhill) came to the conclusion that the available water pressure at our cottage is too low to use one efficiently.

However I managed to buy a large Air Source heat pump for little money last year.

We have E10 electric supply so get cheap electric overnight (5 hours) and for 2 periods (3 hours +2 hours) during the day.

The cost of running the ASHP is a lot less than oil (at the cheap rate), but it will only generate up to 55 degrees output.

My thoughts are that using this to cheaply heat to 55 degrees, then use the oil boiler to top up to 70-75 degrees would give the required heating temp to run the rads, but also allow us to cheaply heat the hot water cylinder overnight and top up twice during the day if needed..

 

[peweuk]

I think the answer may lie here.

http://www.h2panel.co.uk/

It appears to be a combination of motorised valves and pipe thermostats which could be DIY'd.

Or if the price is right, perhaps just buy one to suit the combination of heating units I have.

They have no prices on their site, but I will investigate further.