Halstead combi hot water problem

[hicky]

Ok, I'm not getting hot water from my Halstead Ace combi. First off the system wouldnt fireup, the "nipple" wasnt creating enough pressure to actuate the DHW flow switch ie wouldnt poke out enough.....I've artificialy resolved that and now the DHW system will activate and fire up but it wont produce any hot water. I've got 4 volts across the thermister(chechek its resistance compared to the CH one, maybe 500ohm differance at room temp, the plate exchanger is cold when there is a demand for hot water. The water flow regulater seems fine and the filter is clean.

The CH side works fine.....help, what is the problem????

[cynic]

I wonder just what "I've artificially resolved that" means? It sounds as though your analytical logic and familiarity with the beast in front of you is sufficiently lacking to warrant calling someone in who can deal safely with a gas appliance

[hicky]

Thanks for the help though.

Artificially resolved meant that when the nipple pokes out I'm actuating the micro switch, after that I'm still getting no hot water from the system. =A330 for a flimsy housing and micro switch that is a couple of pound at best from cpc the price of spares takes the mick.

But again thanks for the help

[newshound]

My guess would be the primary side of the DHW heat exchanger blocked with black sludge from radiator corrosion products. These can be washed out. The symptom of this fault is that when you call for DHW and the diverter valve operates, because the DHW doesn't pick up heat through the HX then the "central heating" hot water from the HX over the flames gets hot, this is picked up by the CH thermistor and the gas supply shuts off. Had one of these a month ago, so I know what I'm talking about.

Alternatively, the diaphragm which senses DHW demand may have a hole in it, so the plunger won't move. And on my own Halstead (Finest, Wickes 90) the plunger goes through the middle of the diverter valve, so I think that gummed up parts there will also stop it moving.

I have just developed a split diaphagm and the plunger seems stiff to me: parts on order! And if you think two independent failures in a month is unlucky, I might add that the ignition circuit failed over Xmas, requiring a new board. All this on a five year old boiler which had a new board (kept locking out) and an open circuit solenoid on the gas valve last winter.

Good luck!

[hicky]

Thanks for a more constructive answer, the plunger is free moving just a mm short of actuating the microswitch. I'll give washing the exchanger a try, as I said the circuit is activating but the DHW plate exchanger is freezing. I'll see how I go.