Is my hot water cylinder coil broken?

[paulcantfixit]

Our hot water has been getting colder and colder over last few weeks, central heating has been fine. Plumber has been round and suspects broken cylinder coil but said could not be 100% sure. I am informed that we have a dinosaur of a boiler (stelrad ideal w) our hot water is gravity fed and central heating is pumped on seperate circuit. We have small header tank and a large tank in loft with a cylinder in airing cupboard. When hot water is on boiler fires up but pipework to the cylinder does not heat up. Boiler gets hot and shuts down, then fires again when cool. Plumber spent ages here, bled the pipework but still no joy. Also find when hot water is on some radiators get hot which has never happened before. Apparently there is no diverter valve on our system ?? Before forking out for new cylinder are there any tests that I can do just to make sure its not an air lock.

Thanks for any advice.

 

[royston]

If you run a bath have you noticed any colour in the water ??

 

[paulcantfixit]

We use an electric shower so havent used the bath for ages. Will go a run a full bath now and report back on water colour.

Thanks for your quick response.

 

[moogwai]

in a case of a split coil i came across before the header tank started overflowing as the water from cold feed tank started to back fill into the header tank via the split coil.
Check water levels in header tank and wether it starts overflowing.

 

[paulcantfixit]

Partly filled the bath from hot water tap (water still cold ) colour looks normal and cant smell any chemicals.

One other thing not mentioned previously is that we keep having to bleed air from radiators weekly, this has been going on for months, turned house over but cant find a single leak. Could air in rads be another clue?

 

[moogwai]

sounds like a blockage to me....either in coil itself or pipe work to it. best to drain down system take out cylinder and see if you can get water to flow through coil.....problem is getting a plumber to do this as he will expect to be paid for removal of cylinder and test and put back...even if there is no problem.
best bet is to renew cylinder and surrounding pipework and nip it in a bud.

 

[paulcantfixit]

Just checked header tank in loft. Water level seems to be constant at just over half full, no sign of overflowing. The water in the tank is in pretty poor condition, full of black smelly slimey gunk with white residue floating on top. Never taken the top cover off so never noticed. Could hot water pipework be blocked with this stuff?

 

[moogwai]

Just checked header tank in loft. Water level seems to be constant at just over half full, no sign of overflowing. The water in the tank is in pretty poor condition, full of black smelly slimey gunk with white residue floating on top. Never taken the top cover off so never noticed. Could hot water pipework be blocked with this stuff?

i would say so.....sounds like a good flush will be needed too. Or just renew boiler with a combi and get rid of cylinder and tanks.

 

[paulcantfixit]

The whole system was put in the 80's so cant really fault it. Earlier today the plumber sent water down the vent pipe from a hose, it filled the header tank up with water and slime so knew it wasnt in good nick. Luckily he didnt charge me for the 2 hours of messing about with it because he didnt fix anything so will give him the work if cylinder needs replacing.

Thanks for the help so late in the evening.

 

[moogwai]

definately got blocked pipework then.....get him to renew the pipework around cylinder before renewing it......and again i would give the whole system a good flush..or it'll just happen again. And fair play to your plumber.....see there are a few decent ones out there. good luck.