DIY Doctor UK DIY Forums

Hi,
New member requesting advice please.
I have a three story house , I am struggling to heat the ground floor above 16 degrees, one radiator is randomly hot or cold, the top 2 floors are a lot hotter and most radiators are consistently hot.
I have replaced the wall thermostat which is downstairs, it shows 16degrees set at 21 degrees - constantly calling the boiler for more heat - boiler runs for approx 2 mins cuts out and will restart and run again for approx 2 mins .!!!!

I have had a plumber examine the system and has recommended a replacement pump, he examined it and said even though it is circulating it is under performing, hence the reason for the boiler cutting out and the slow increase in temp of system. Also accounts for random cold rads . Further more because the piping is 10mm microbore the system should be flushed and a magnetic filter installed to support with annual inhibitor.
Finally he advised upgrading one of the downstairs rad
Total cost £700.

Whilst I can understand his logic I am unsure as to whether this is the solution .

If I turn the central heating off and just select hot water the boiler still only keeps cutting out and back on - would this be the case just for hot water - what part does the pump play for HW??

The system is a standard boiler ( not combi) cylinder on top floor fed from separate header tanks in loft.

I need to resolve this as currently to maintain heat and water the boiler is running all day constantly turning on and off in an attempt to raise maintain C/H temp and hot water.

All you experts please excuse my inexperience any words of advice and reassurance before I part with £700 that may or may not resolve the problem

Regards
RED

Its one of the pains with a microbore system. Whoever invented it should be shot. your engineer is possibly quite right on his suggestions using an acid flush though. This is not just a flush through & requires speciality equipment. It will also find any other minor faults you have. Not sure on the pump replacement part unless he has done some sort of flow rate test.
Its quite likely thew lower rads & pipes have a build up of crap & need the flush through.
Mag filter around £100.00
Rad £100.00
Inhibitor. £25.00
Pump £100.00
Price for flush depending on how its done. ?????
Half days labour for the engineer & a mate.
So the price is not far off.

There are a number of things which ensure even distribution of the heating water, the friction in the pipes, pressure of pump, difference in temperature, the TRV, and last but not least the lock shield valve, and since the lock shield valve is easiest to adjust, that must be first thing to try.

In theory you should use the temperature of in and out pipes, but turning down working radiators will often work, you start with a radiator near boiler, turn off lock shield valve completely, let radiator cool then open counting by 1/4 turns with at least 1 minute between each 1/4 turn and stop as soon as you feel heat.

If all same make then turn off all lock shield valves on working radiators, and open then number of 1/4 turns counted. That will normally force water through radiators not working.

But main point is work on working radiators, not those not working.