hot water pumping into header tank

ninja.turtle007

Please help!!

When my central heating is turned on it pumps hot water into the expansion tank. It is an old system probably about 20 years old.
I had a plumber come round and he said i should replace it with a combi for £2000. This seems to be a lot of money seeing as the rest of the system seems to work well still.
I have tried putting some chemicals into the system to clean it and left for about a month before emptying today. The water seems to be only slightly murky.

What can i do?

ariba10

There may be a speed control on the pump, if there is turn the power off and slow down the pump.

It may also happen if you have only one or two radiators tuned on.

ninja.turtle007

Hi, thanks for the reply.

The pump in on number 1 and all of my radiators are on (9).

Avoriaz

It could be a system design fault.

Does the expansion pipe branch off just after the pump?

This could be the cause of the problem as the pumped water will find the route of least resistance. If this is up the pipe, there is your problem.

Moving the point at which the expansion pipe branches upwards so that it is further away from the pump might solve the problem.

ninja.turtle007

If that was the problem surely it would have come to light when the system was installed 20 years ago?

I thought it may be a partly locked pipe somewhere. What do you think?

John_3:16

It could be a blockage. Go Back and think. when did it start do all the rads get red hot are there any cold spots in the system as the the water is being pumped into the tank I asume it is also taking water out.

ninja.turtle007

It has been doing it since we moved in 18 months ago. All of the radiators upstairs get hot if the pump is set to 1. For the downstairs radiators to get hot the pump has to be running faster.

John_3:16

At what rate would you say the water is pumped into the tank and is it very hot?

ninja.turtle007

yeah it's hot. In fact the steam given off has caused mould in the loft room. The amount of water depends on the speed of the pump. On setting 3 probably around 1 litre per min + or -

EliteHeat

ninja.turtle007 wrote: »

I thought it may be a partly locked pipe somewhere. What do you think?

You're absolutely right unless of course you have a completely blocked section of pipework.

Assuming it is partially blocked a powerflush in conjunction with the right chemicals should fix it. It might also be a good idea to have the pipework reconfigured if it is not installed to current best practise.

Powerflushing is quite expensive although I'm sure that I will be flamed by people who paid a tenner for it and the heating engineer was glad to get it for a days work etc etc.

Canucklehead

Hi

If you post a photo of the cupboard, or where ever the pump and pipework is situated, it would make things a lot easier.
It sounds like it's been doing it for some time and may well be a basic problem that can only be cured by altering pipework.

Corgi Guy.