I may need an additional CH pump

[moh222]

Hi
I have a 3 year old Ariston 24kw combi boiler in my house connected up to 9 radiators now. I have a magnaclean pro 2 next to it on the return as well.
It was working beautifully when I had 7 radiators, when I added an 8th one in downstairs loo it struggled to heat that one up, so I balanced the system using an infra red thermometer and then it worked perfectly. Now that I have the 9th radiator I am back to the same problem, bleed out all the rads and balanced again but still that 9th radiator takes forever to heat up. I think my thermometer is struggling to get good readings so Im gonna get a K-type thermometer very soon with clamps for the pipes to get more accurate readings.
But I personally think one issue seriously affecting my problems is the pipework, my boiler is in attic and some of pipework on 1st floor and all in attic is 22mm but rest of house is 12/15mm esp ground floor where the new rads where added, problem is builders cut corners when I had an extension build and I dont think they added more supply and return loops but simple extending the pipework in 12/15mm creating more bottleneck for the heat, so my ground floor rads are last to heat and the furthest one my 9th rad takes foreever.
I remember seeing only 12/15mm pipes between 1st floor and ground floor when we had the chimney removed 2 years ago.
I cant see anywhere in my boiler manual where the spec of the pump is, it doesnt say what flow rate the pump can do, and also theres no mention of any adjustment so I assume you cannot adjust it.
Question would it be wise to add another CH pump near my boiler to reduce bottleneck on my ground floor and wire it in parallel to internal boiler pump so it comes on at the same time ?
Im a fully qualified electrician, but only have basic knowledge on plumbing issues. Wiring and wiring diagrams are no issue for me at all.
What do you think ?


Thanks

Mohamed.

 

[footprints]

Yes sounds like your pipework is undersized, never had to double up a pump on a system in 40 years!

You really need a heating engineer to look at the system as a whole and re-pipe where needed, one of those jobs where you need to be on-site to advise rather than guessing from information posted I'm afraid.

 

[Agile]

It would be very unwise to fit a second pump. For a start its unnecessary and to end it might well upset the boiler operation.

The correct solution is to solve the problem pipework but you will probably say you cannot access it.

Your problems are because you let a builder mangle your system instead of a proper heating engineer.

You will probably improve the situation by balancing with a greater flow pressure. Find the rads on the proper sized pipework and close the lockshield far more. Usually only open about 1/2 turn.

Then try to get the flow to the coolest rads with their lockshields open about two turns.

Tony

 

[Plumber90]

What make and size pump do you currently have at the moment.

 

[picasso]

Stick a plate heat exchanger on the flow and return from the boiler,then you can use a second pump to overcome the undersized pipework.

 

[moh222]

I can't change pipework now as a lot of it is tiled over under floor boards or concreted over in extension.
As for the pump I don't know the specs of the pump in the boiler bit I will call ariston over next few days to find out.
I guess I will have to tweak the lock shields more, waiting on new k type thermometer with pipe clamps.

 

[moh222]

Spoke to ariston today, and they informed me I would not need another pump unless I was running microbore pipework. They told me the pump is a 5metre head, I assume they mean a 5 metre per hour head.
More radiator balancing to do I guess.