Pump in return flow

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10 Dec 2004
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Apparently the pump in my central heating system is fitted in the return flow as opposed to the forward flow. Can anybody tell me what problems this is likely to cause? Do I need to get it fitted properly?
Yes I am having problems with the CH but I dont know if these problems are related to the pump!!

:rolleyes:
 
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The main problem is that the pump is sucking water around the system, causing the majority of it to be under negative pressure. Any microleaks you may have in the system will result in air being drawn in. The resultant oxygenation will contribute to corrosion of your system, leading to premature component failure, reduced efficiency and possibly the end of life as we know it.

This is now considered to be not "best practise" :)
 
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Thanks for your guys.

I've got 2 cold rads downstairs, all hot upstairs, balancing didn't cure the problem, and the pump seems to be running ok to me. All rads have been bled. Turning off all rads except the cold ones cures the problem temporarily, but the next day they don't come on again. I assume the colds rads aren't blocked as they do come on when all other rads are off.

Anyway, I wondered if the pump in the return flow was a contributary factor. or perhaps the main source of the problem.
 
sounds like you have a gravity system with pump being on return very good chance the antigravity valve is partially blocked. it should be on the flow pipe from boiler usually within a couple of feet. sometimes a gentle few taps with hammr will clear blockage for mean time ,but best to change valve
 
Hi

Was it the anti- gravity valve? I have the same problem, its an old gas back boiler with grudnfos 15-50 pump fitted on the return flow. The HW is gravity fed i think. Its the original system from when the house was built in the 1960's. The upstairs 3 rads get hot at the top half but not the bottom, the 2 rads downstairs only get hot at the very top and sides (few inches) only, but not on the bottomw at all. I suspect their is sludge blocking them aswell but the is also a flow circulation problem. I have a single pipe system i think. The pump is under the ground floor and the back boiler in the lounge. I have something that looks like an anti gravity valve on a verticla pipe in the airing cupboard in the upstairs bathroom where the HW storage tank is fitted. The pump seems to be spinning okay from what can be seen by the inspection cap an di have tired bleedig the rads and putting the pump on full speed but nothing has helped. Could it be anything else causing the flow to be so poor?
 
Hello, Fazal. I think you need to set up a new post rather than piggy-back on this old one (I made a similar mistake when I first arrived). :oops:
 

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