central heating shuts off after 30 seconds radiators only slightly warm.

[gold7]

Hi all excellent forum . I did try to search for the answer to my query but no joy , I'm a new plumber and don't have much experience at diagnosing heating problems at all.

A friend of mine asked me to pop round and check why he's heating wouldn't work, i couldn't spend much time there as i was in a bit of a hurry,

heating goes off after 30 seconds and rads are just slightly warm .

boiler was valiant cant tell you the model I'm afraid, it had an unvented cylinder next to it , set up is in loft. with the time i had i just bled the rads which I could get to, they were the ones on the end of the heating circuit (no air) and i played around with the controls or should i say turned the boiler off and on a couple times.

I'm due to go back there with in the next two days to have a proper look just wondered if one of you experienced heads could help me diagnose or give me a procedure to follow please. I was thinking it's a circulation problem so could be a pump but dont know how to check apart from listen to check if its working , I apologize i must sound like i havn't got a clue its just that i'm not experienced in this line of work. And every ones starts some where i suppose.

Thank You.

 

[Bernie2]

Hmm!

Turn off electricity.

Usual way to check pump, is to take the large cap off in the middle of the head and make sure spindle is turning. But if its an eco tec it looks like you can't, so its a case of either taking it out to test, checking resistance. Listening to it run. Get a piece of wood and place it on the body of the pump you can usually hear the impellers turning.

You can of course open the auto air vent manually or open a test point and see if the water pressure picks up when you turn the pump on.

Its all a matter of thinking how you would detect an increase in pressure and depends what there is to do it with i.e. test nipples, bleed points and so on. And electrically by checking pump line fuses, power supply and resistance with a multi meter.

A resistance check tells you the motor is alright, but it will not tell you if it's turning the impeller. If the motor gets hot very quickly the chances are its not turning the impeller.

If its safe turn back on and with cap nut removed watch the impellers turn.

But you can get water coming out of it, so go careful.

 

[dontknowitall]

This is a brilliant book:

Central Heating Repair, Plumbing Book, Fault Finding, DIY, Professional and NVQ Plumbers

 

[Deleted member 2053]

Hmm!
Usual way to check pump, is to take the large cap off in the middle of the head and make sure spindle is turning. But if its an eco tec it looks like you can't,

Ecotecs use the pressure switch to detect the action of the pump and fail with an F75 if there is no change. Probably not an ecotec.