central heating radiators only lukewarm

I have a very old Ideal E type boiler. Last month the central heating radiators were only getting lukewarm when I turned the heating on the radiators remained lukewarm and the hot water stopped getting very hot. The hot water without the heating is working perfectly fine.

I had a gas engineer come and have a look at the problem and he informed me that I need a power flush because this problem is caused by sludge in the system. I had the power flush done and the system got a little better but then the same problem again. I called the same heating engineer and he came and changed the pump and the system improved but now we are again where we started. We can't just keep on changing pumps every month!

I called another engineer and I told him how the first engineer had done the power flush and he has informed me that he has not done proper power flush as you have to do it radiator by radiator whereas he only did it while all the radiators were on. He has asked me to get first engineer back in again to do the proper power flush. But this engineer keeps making excuses and is not coming.

Can someone please give me suggestion of what is happening with my central heating system? I have been informed by both the engineers that 2 port motorised valves are working fine. The 2nd engineer has advised me to get the system power flushed properly (i.e. radiator by radiator) and then to install a new pump because the current pump although working does not have adequate power to push the water through the radiators and that is why I am getting these problems with my system. Additionally there is one radiator downstairs that is only getting lukewarm like all the other radiators but only at the top which suggests that there is sludge in this radiator.

Any suggestions and comments would be much appreciated

add some cleaning chemicals ie sentinel x400 leave in system for a couple of days while running the heating system, then have that wolly gas man back to powerflush the system (one radiator at a time) make sure he closes the htw circut tho..

fit a new grundos pump then hopefully your system will work, that is assuming the boiler is ok.

onlyfitidealboilers said:

add some cleaning chemicals ie sentinel x400 leave in system for a couple of days while running the heating system, then have that wolly gas man back to powerflush the system (one radiator at a time) make sure he closes the htw circut tho..

fit a new grundos pump then hopefully your system will work, that is assuming the boiler is ok.

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What do you mean by closing hot water circuit? Do you mean only central heating on? Also I presume that the boiler is working fine if there is no problem at all with hot water, therefore what do you mean when you say that the boiler is ok?