Installed central heating 2.5 yrs ago worcester bosch junior 28i etc, fitted a cheap Horstmann programmable roomstat, never used the programs, just turned the temp up and down to control heat.

Last week thermo was showing on but no boiler or heat, although hot water working ok, fiddled around with things reset boiler etc , and after a while for no apparent reason the boiler fired up.

This morning again heating side of boiler not working , checked roomstat again , checked with mains testing screwdriver , power at roomstat and inside the boiler.

Feared the worst , got extortionate quotes from Worcester Bosch and B.G for repairs.


In one final desperate attempt I removed the wiring to the roomstat and put a wire loop back in boiler , much to my amazement and good fortune it fired up!!!!!!


So can I assume that while the roomstat was switching and making a connection , for some reason it could not carry enough current to operate the boiler.


I would be interested to know of any other similar experiences!

No, I don't have a similar experience, but I believe it's well worth your while renewing the roomstat?

I recently replaced the diverter diaphragm in a Halstead boiler that wasn't producing hot water. Locost approach, stripped the valve and replaced said diaphragm (£10), rather than replace the whole unit (£lots). Reason for my involvement (for an elderly relative) was that she'd had the 'engineer' over to fix the problem, he simply swapped over fully working circuit boards, proclaimed the boiler 'fixed' and left said mother-in-law deprived of a *a lot* of cash. Nice.

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Reason for my involvement (for an elderly relative) was that she'd had the 'engineer' over to fix the problem, he simply swapped over fully working circuit boards, proclaimed the boiler 'fixed' and left said mother-in-law deprived of a *a lot* of cash.

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Originally posted by Surrey Dave
This morning again heating side of boiler not working , checked roomstat again , checked with mains testing screwdriver , power at roomstat and inside the boiler.

In one final desperate attempt I removed the wiring to the roomstat and put a wire loop back in boiler , much to my amazement and good fortune it fired up!!!!!!

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Originally posted by motorcycle_mayhem
No, I don't have a similar experience, but I believe it's well worth your while renewing the roomstat?

I recently replaced the diverter diaphragm in a Halstead boiler that wasn't producing hot water. Locost approach, stripped the valve and replaced said diaphragm (£10), rather than replace the whole unit (£lots).

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Originally posted by clairetoo

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Originally posted by motorcycle_mayhem
No, I don't have a similar experience, but I believe it's well worth your while renewing the roomstat?

I recently replaced the diverter diaphragm in a Halstead boiler that wasn't producing hot water. Locost approach, stripped the valve and replaced said diaphragm (£10), rather than replace the whole unit (£lots).

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Interesting..............I have a Halstead boiler which will only make warm (rather than hot) water when the tap is turned full on - any less and the boiler cuts out
I wonder if it's the same problem - and if so , where can I get the parts to fix it myself ?

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Originally posted by adam1985

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Originally posted by clairetoo

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Originally posted by motorcycle_mayhem
No, I don't have a similar experience, but I believe it's well worth your while renewing the roomstat?

I recently replaced the diverter diaphragm in a Halstead boiler that wasn't producing hot water. Locost approach, stripped the valve and replaced said diaphragm (£10), rather than replace the whole unit (£lots).

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Interesting..............I have a Halstead boiler which will only make warm (rather than hot) water when the tap is turned full on - any less and the boiler cuts out
I wonder if it's the same problem - and if so , where can I get the parts to fix it myself ?

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sounds like the dhw heat exchanger full of crap

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Claire,

Before thinking about DHW exchanger I would seriously check the ntc sensor first,When the water is cold the resistance will be higher on the the ntc,when the temp gets up the resistance will drop.

When the water is cold the resistance is likely to around 16ohms dropping to approx 8 ohms when warm( this is tested using the 100ohm setting on my meter)

Turn of electrics to boiler,Ntc has a 2 pin socket and resistance can be measured by putting black and red lead to 1 pin each.

If the resistance is low the water will never get fully hot as the resistance from the Ntc is what modulates the gas valve.

Hope this helps

I have a halstead boiler which had a problem with the hot water supply only getting warm, the weird thing was that the radiators warmed up when the tap was on. I looked at the boiler diagram and saw something called a diverter valve I assumed that water was being diverted to the heating so I changed the part et voila all working well.

So run your tap when the heatings been of a while and see whether they warm up if so change the diverter valve

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Originally posted by craig_007
When the water is cold the resistance is likely to around 16ohms dropping to approx 8 ohms when warm( this is tested using the 100ohm setting on my meter)

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clairetoo:

To check the diverter valve, simply look at the top of it and turn the hot water on. The piston should rise under the microswitch. If it doesn't - I'll wager it's the diaphragm failing. Lots of sources for diaphragms (even Ebay), cost £10. It isn't worth buying a replacement unit, just get the rubber bit inside it. If the microswitch IS triggered and nothing's happening, doubt the microswitch. A full wiring diagram (free) is on the web from Halstead, so you can check.
If it's all working, yep, your heat exchanger is full of crap. It's the grey thing to the left, simply replace. Wiltshire water is basically saturated carbonates, so it chokes everything, very quickly.

And yes, this is something you can do. In fact there is nothing you can't.

dont replace heat exchanger clean it in ds40 from plumbcentre(£25) enough to do 3 or 4 times new plate around £100 if you need any advise u2u me.........................

Hi folks

I was under the impression that taking the cover off a gas boiler was illegal unless Corgi registered, or is it the case you can work on a boiler if your not doing it on a trade basis?

Regards

Geoff

if competent you can do what ever you want.....being gas safe formally corgi registered just proves that you have proved to someone that you are competent.........most people get prosicuted for claiming they are gas safe formally corgi registered when they are not..........if in doubt ask

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Originally posted by motorcycle_mayhem
clairetoo:

To check the diverter valve, simply look at the top of it and turn the hot water on. The piston should rise under the microswitch. If it doesn't - I'll wager it's the diaphragm failing. Lots of sources for diaphragms (even Ebay), cost £10. It isn't worth buying a replacement unit, just get the rubber bit inside it. If the microswitch IS triggered and nothing's happening, doubt the microswitch. A full wiring diagram (free) is on the web from Halstead, so you can check.
If it's all working, yep, your heat exchanger is full of crap. It's the grey thing to the left, simply replace. Wiltshire water is basically saturated carbonates, so it chokes everything, very quickly.

And yes, this is something you can do. In fact there is nothing you can't.

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