Plumbing Help!

[indykid]

heat travels the shortest way possible the same is with the pump it would back flow taking the shortest path back to the pump again even with reduced flow on the rad itself

I presume you're talking about the purple route, Gaz?

I'd want the pump on the lower end of the back boiler (green dot) and make that the return. Counterflow is more efficient from a heat transfer perspective than co flow, but going co flow, you get the benefit of thermosyphon assisting with the pumping. If you're changing the flow direction on the rads, you might want to shuffle any TRVs around to suit though.

 

[RichardM]

Have a look at your header tank, is there a vent pipe to it? Our system is a pain to bleed if the vent is blocked. I use a piece of 8mm nylon airline pushed down the vent pipe to break up any blockage.

 

[gaz1]

i will give you some pics note how they run

with pumps and zone valves they suffer heat and burn out faster on the flow side whilst they do last longer on the return side of the system
you can use pumps and zone valves on both return and feed pipes but you will replace more of them during the life of the system on the feed side

you can use a y valve 3 way zone valve that returns to open when a power failure hits with a gravity fed system is used that gives pumped assist to a gravity fed system but returns to gravity fed during a power failure ( old plumbers know this detail )

its best practice to have the tank feed further away from the pump as it tends to pull water from the tank as well as the system if its too close it does pull hard from the tank hence why you get alot of excess being pushed back up the overflow of the tank feed system

 

[fizzy]

May or may not work in your case but I have had amazing results bleeding hot water pipes and pumps using an aquavac! Just suck it through. I know they use vacuum brake bleeders for this reason as well.

 

[Beeezer]

I don't see a vent over the header tank.
[/QUOTE]
The header tank is open topped.

 

[Beeezer]

how's the header tank plumbed up? pipe as photo straight into bottom of it? does it get hot?

Yep, pipe in bottom and yes it gets warm when working.

 

[Beeezer]

May or may not work in your case but I have had amazing results bleeding hot water pipes and pumps using an aquavac! Just suck it through. I know they use vacuum brake bleeders for this reason as well.

Good idea, garage I work at has a vacuum pump.

 

[Kayos]

Header tank doesn't need a vent if the boiler has a high limit stat (or can be used sealed)
Combined feed and vent still needs to go behind the pump, and a long run can airlock