Poor circulation on central heating.

[puntaprimapete]

Further to my posts of a few weeks ago. I have now had my system power flushed. It did wash out a lot of crap but it has made no difference at all. Got the engineer back in from heat team who has now fitted a new pump Still no difference! If the upstairs rads are on the downstairs ones are cold. I talked to the engineer about the possibility that the new rads and larger bore pipes I have fitted have created too much resistance and maybe thats why it flows upstairs and not down. Finding the path of least resistence. He thought this was a definate possibility.
I thought I might help the problem by installing a second external pump on the downstairs circuit.
Any thoughts on this would be greatly appreciated.
Cheers
Pete

 

[Bahco]

Have you balanced the system

 

[Agile]

Yes, balancing might be the clue!

Is it microbore?

Tony

 

[puntaprimapete]

I have tried balancing but even if I shut down the valves on the hottest upstairs rads I am barely getting any heat downstairs with the valves fully open. It's not microbore. I had 3 old rads downstairs that were on microbore but I replaced these and used 15mm. This is why I'm wondering wether the new rads with bigger pipes have caused too much resistance and the current pump is not able to cope.
Is it possible to fit a 2nd pump? If it is I think I'll give it a try. I've spent a fortune getting nowhere up to now so what's another £40 or so.
If I did fit one are there any tips as to how I should wire it up? It would be a long way from the boiler so I thought I might be able to wire it up to a room stat? so it comes on when heat is needed in that area.
Has anyone ever done this before?

 

[Bahco]

Bleed the pump. See FAQs

 

[kevplumb]

If I did fit one are there any tips as to how I should wire it up? It would be a long way from the boiler so I thought I might be able to wire it up to a room stat? so it comes on when heat is needed in that area.
Has anyone ever done this before?

have done it before in a pub one on the flow another on the return

but you really want it wired back to the boiler

 

[tonybhoy]

You could always stick a pump in with a temp wiring setup and see if it works.

Just stick a cable and a plug on the pump and switch it on when you have the heating on with the original pump.

Either that or go for a bigger pump,you can fit a one inch pump,your current one will be a 15MM internal bore which is what the 15 stands for in the 15-50 or 60.

You are talking about £180 for a one though.

Give this lot a phone if you decide to go down that route be aware though that your existing pipework will more than likely be only 22MM but these bigger pumps should still work.Having said all of that there may be a blockage in a part of your heating system that no amount of pumps are going to shift.

http://www.ferrierpumps.co.uk/

 

[D_Hailsham]

I have tried balancing but even if I shut down the valves on the hottest upstairs rads I am barely getting any heat downstairs with the valves fully open.

You need to start with the rad nearest the pump when you balance a system.
Leave the control valve fully open and use the lockshield valve to balance.

The lockshield valve will be almost closed on rads near the pump and will be open more as you get farther from the pump until the lockshield on the last rad may be fully open. Ideally you need to be able to measure the temperature on the flow and return pipe to each rad to balance the system properly.

If you have TRVs on any rads, remove the top so the TRV does not work.

Footnote

In your earlier topic you said:

We knew that the return was nearly stone cold, the feeds to the radiators were scalding, the flow from the boiler was scalding, the flow from the motorised valves was scalding and the return from the Hot Water Cylinder was stone cold.

But you also said that you had a Baxi 105HE combi boiler. How do you explain the motorized valve and the Hot Water Cylinder?

 

[puntaprimapete]

Hi That quote was not from me I definitely do not have any valves or a hot water cylinder.
I have been tinkering with the balancing again and have managed to get some heat to another rad. I think that's about as far as it will go though because if I shut down the hot rads any further they just go cold.

 

[hedsa]

Has the filter in the return isolating valve been checked / cleaned

 

[Slugbabydotcom]

Has the filter in the return isolating valve been checked / cleaned

Just what I was thinking
I have just been tortured by a similar thing on a VCW
This looks as though the valve is open doesn't it?

Untitled

• Slugbabydotcom
• 3 Apr 2008
• 1

Oh no it isn't

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• Slugbabydotcom
• 3 Apr 2008
• 1

I think you can see when you look closely at this pic below that the valve is only open enough to let a little water through. I reckon it is open by the equivalent of a half squahed 8mm pipe.

Untitled

• Slugbabydotcom
• 3 Apr 2008
• 1

Similar scenario
Upstairs rads got lukewarm. Downstairs made it to tepid at one end. Boiler lit and cut out in about 20 seconds.

 

[puntaprimapete]

Hi, i've checked the filter on the return valve and it is spotless. I haven't removed the valve to check it's fully open but it is clearly in the open position. Was the valve in your pic broken?
I will check this on mine asap.
Thanks
Pete

 

[Slugbabydotcom]

Yes it was broken.
In this case. Look at the line on the square operating part of the valve . The logic is that if this line is in line with the water flow it is ON. If the line is across the pipe it is logically barring the water from passing = OFF
With the valve in the position shown you should have been able to see right through the valve when looking down the end of it.

I turned the boiler valves to the off position and let the water out of the boiler through the PRV. When I turned the filling loop valve on then the boiler mysteriously refilled. This proved that either flow or return valve was not functioning correctly. By turning valves on and off whilst listening to the tone of the water rushing through I deduced that it was the return valve that was faulty.

 

[D_Hailsham]

Hi That quote was not from me I definitely do not have any valves or a hot water cylinder.

Just looked it up again. It was in another contributor's explanation to you how he located a blockage.

I have been tinkering with the balancing again and have managed to get some heat to another rad.

What speed setting do you have the pump on? According to the Installation Manual it has to be on 3.
Is the return pipe to the boiler still cold?
If so do you have any idea what the temperature is?
What is the CH flow temperature set to?

Tinkering with balancing will get you nowhere; it has to be done methodically.

As Softus said in your previous topic, work out the layout of your system first. Then start at the rad nearest the pump and go in sequence along each branch.

I think that's about as far as it will go though because if I shut down the hot rads any further they just go cold.

I take it you are talking about closing the lockshield valve. Unfortunately, due to their design. most rad valves are only effective over about the first 25% of the range from fully closed to fully open. It's called "valve authority".

I also think you may not understand how balancing works. The more you shut down the lockshield valve on a radiator the slower the water will flow through the radiator and the higher will be the temperature difference between the flow and return pipes of the radiator and, consequently, the greater will be the heat output from the radiator. (The heat output from a radiator is proportional to the difference in temperature between flow and return.)

I suspect that you are closing down the lockshield valve thinking that this will make the radiator cooler. It will - when the valve is fully shut, as you have found. I suggest that you start from scratch by opening all lockshield and control valves on all radiators and then balance each radiator in turn starting from the ones nearest the boiler

It would be worth reading Balancing TRVs. Although it is about systems with TRVs, the instructions are relevant to all systems.

 

[namsag]

You say used to be microbore do you still have the rads coming off the microbore manifolds and just increased the size of the pipe after this or did you tee into the 22mm and are any of the rads off the microbore manifolds