Pump over and expansion pipe location.

[AndyTh]

Hi again, second post, different issue but same house as my first post about wiring.

I have added extension to house and now have 2 pumps each supplying 2 single valves for CH and HW. Boiler is Worchester CDi conventional with a header tank and supply and expansion pipes. Since house is single story barn, and pump is in attic, there is only approx 9 ft head from pump to tank. The pumps are mounted on the return side of the boiler as is the supply from header. The expansion pipe is on the flow side of the boiler.

Problem is that with the pump on, I get pump over --up the expansion pipe and back via supply. This also makes it impossible to bleed radiators etc. Problem is solved by closing valve on expansion pipe. Not recommeded.

Any better solution?
I could install an auto bypass valve on the expansion pipe set for 2 or 3 bar. This would only open if supply pipe was blocked or other emegency.
I could install autobypass from flow to return side, but not sure how to set this up.
I could plumb expansion pipe to return.
What do you recommend?

Cheers

 

[snowhead]

Who Designed / Installed this system or addition?

If it was Professionally done, get them back to sort it out.
If it was all done by yourself, employ someone with experience to sort it out, it'll be cheaper and safer than messing around with it yourself

 

[PhoenixServices]

Feed and expansion not in correct position so not in the neutral part of the system needs reconfiguring correctly by the sounds of it.

 

[PhoenixServices]

This system sounds butchered, need a few pictures of pipework layouts.

 

[Rickster123]

Who Designed / Installed this system or addition?

If it was Professionally done, get them back to sort it out.
If it was all done by yourself, employ someone with experience to sort it out, it'll be cheaper and safer than messing around with it yourself

This^^

 

[lame plumber]

should have gone unvented from the star tno need for tanks then

 

[jtsplumbing]

I'm Sure that you can download diagrams on best position for pump & position of cold feed / vent pipe , does it show anything in installation book that is with boiler ?? Not a good idea to put a valve of any sort on expansion pipe

 

[AndyTh]

Sorry if I am raising the same topic in two threads - I thought they were separate but perhaps they are related.

I have just made the post below under the topic of wiring for pump overun

I have now made a diagramof thesystem - see below. I know the system is not as per modern practise, but the original house system was done as below the dotted line. The new extension is a parallel system above the dotted line (installed by builders and plumber). We will mostly live in the new extension unless the kids are at home in which case the original system needs to operate also.

There are three problems
1. pump over via the expansion pipe,
2. I suspect that the boiler keeps both pumps running, even if the demand is only for one extension and thus the pump will deadhead.
3. all the valves close while the boiler is in overrun and the pumps deadhead.

I know that it is meant to be boiler, expansion, supply then pump, but that is a major reconfig that i was hoping to avoid.

What solution do you recommend.
1. I could install relief valve and go unvented - I was trying to avoid that.
2. I could just install a pressure relief valve on the expansion pipe.
3. I could install relief as above and auto bypass - one for each circuit
4. I could try to managewith one pump - but it is a big system for one pump
View attachment 24411

 

[jtsplumbing]

. What s the output on boiler / can it cope with extension ? Is pipe size large enough to cope with extension ? You need to call someone in to look at what you are planning to do, don't go down the route we never use all of the system, look on worse case there will be a time when you need to run all of the system How will it cope