Hi,

 

A friend asked me to look at his sisters heating today, the downstairs rads are not right. The two larger ones at the front (furthest from the boiler) just don't heat up and the 2 smaller ones take an age to warm up. I'm thinking both sludge and balancing as the flow pipework up to the rads gets hot but the rad just takes for ever.

 

I tried shutting down rads and trying to force the hot water round the radiators but still so slow to heat up. Pump is already turned up to max.

 

I wouldn't say the upstairs rads are brilliant either..........

 

It's a conventional system. Any ideas on things to try next?

 

Cheers

 

Vijay

Is there an easy way of telling if it's a 1 or 2 pipe system?

 

Also noticed there is a an automatic by-pass valve fitted, is there a way of testing that to eliminate it?

check the divertor valve Vijay...find the 3 way valve it willhave a motorised actuator on the top or side of it ....usualy near the pump.....go to the control unit and get somebody to switch it to hot water only while you look at the the valve you will hear it move and see the pin slide to a new position , now ask your helper to select heating only the valve will move again and the pin will slide ....select both hot water and heating and the valve will divert to both systems ....these valves are notorious for sticking .....you can move the slider pin by hand to alter the diverting flow if you need to if they break down .......

Hi Steve,

 

It has 2 x 2 way diverter valves instead of 1 x 3 way. All the pipes coming and and out of both of them are hot but I will try what you said :)

HI MATE i am a heating and plumbing engineer ,the pump sounds like it is goosed or full of crap ,or the diverter valve sticking .if not drain down system and power flush with cleaner .strip of rads and wash through with hose . drain down cylinder as well . refit everything also get a magna clean fitted worth there wheight in gold look them up on website pull out a lot of magnatite etc . fill all system back up and add inhibitor . But it does sound like pump impellor goosed and not pumping water round system .But my advice get a combi fitted saves a lot of chew .there are some good ones on market and not pricy ,if I can offer any more advice feel free to mail me

I did what Steve suggested and the diverter valves are moving. I removed the screw on the pump and it is spinning (I put the tip of the screwdriver in it and can feel it move - is there any other way of testing it?) Is it worth removing and taking apart to check???

 

I drained down the system on Thursday and put some Fernox cleaner in it and been running it since then. Checked today and it's still doing the same thing. The only rad that works properly is the bathroom rad which is the nearest to the boiler/diverters/pump/automatic by-pass valve. One other rad in the front of the house seams to be working OK too which is a slightly larger one. The two other bedrooms rads are warm and downstairs, 2 smaller ones have slight warmth and the 2 larger ones are stone cold.

hi Vijay

 

the pump may be making the right noises but doing nothing inside the pump body, i would be looking at taking the pump out of line and running it so you can see inside the pump body and watch the impeller go round ...to do this you would be draining the system anyway ...so whilst it is down and bled remove all the rads and flush them with a hose pipe outside near a drain ....they take some flushing by the way till they run clear, a magnaclean are brilliant i have one fitted by BG whn ethe changed the heating system a few years ago ..its full of crud very time i clean it ..saves a lot going into the system ..as the black crud is mostly magnetic it sticks to rad pipes and walls and is difficult to shift with just heating watre pressure it needs a good full power flushing to move it ....sounds like the system needs a good old overhaul