Surrey Dave
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| posted on 16/2/10 at 02:06 PM |
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Heating Engineers , Is This Fault Common??
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!
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motorcycle_mayhem
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| posted on 16/2/10 at 02:40 PM |
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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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whitestu
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| posted on 16/2/10 at 03:21 PM |
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quote:
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.
There are plenty of useless / dodgy plumbers out there!
I had to do my own wiring on our heating control valves - 2 different plumbing electricians couldn't work out how to make the hot water come on
independently of the heating!
[Edited on 16/2/10 by whitestu]
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MkIndy7
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| posted on 16/2/10 at 04:59 PM |
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quote:
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!!!!!!
There is always a constant 240V supply to a combi boiler so it can run 24hrs a day when the programmer is off, when you open the hot water tap.
It gets a further Run signal from the programmer, via the roomstat to the boiler to make the heating side of it work.
Alot of the time they are 0v contacts, a basic continuity circuit to make it run, hence why when you link the 2 terminals out they run.
I'd say its down to the Wireless programmer circuitry somewhere, have you still got the instructions to follow them?
Tried new Batteries?
Paired the reciever and the Stat/programmer?
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clairetoo
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| posted on 16/2/10 at 05:18 PM |
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quote:
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).
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 ?
Its cuz I is blond , innit
Claire xx
Will weld for food......
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adam1985
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| posted on 16/2/10 at 06:04 PM |
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quote:
Originally posted by clairetoo
quote:
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).
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 ?
sounds like the dhw heat exchanger full of crap
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clairetoo
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| posted on 16/2/10 at 06:16 PM |
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quote:
Originally posted by adam1985
quote:
Originally posted by clairetoo
quote:
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).
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 ?
sounds like the dhw heat exchanger full of crap
? ? ?
Would that be something I could fix ?
Its cuz I is blond , innit
Claire xx
Will weld for food......
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craig_007
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| posted on 16/2/10 at 09:16 PM |
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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
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austin man
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| posted on 16/2/10 at 09:52 PM |
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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
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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MikeRJ
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| posted on 16/2/10 at 10:49 PM |
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quote:
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)
Do you mean kOhm? Those resistances are extremely low for a thermistor, like at least a couple of orders of magnitude.
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motorcycle_mayhem
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| posted on 17/2/10 at 09:35 AM |
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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.
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deanwelch
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| posted on 15/3/10 at 10:39 PM |
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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.........................
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locogeoff
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| posted on 15/3/10 at 11:33 PM |
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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
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deanwelch
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| posted on 17/3/10 at 08:19 PM |
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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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clairetoo
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| posted on 22/3/10 at 06:03 PM |
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quote:
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.
I had a good look at the boiler yesterday , as things have got worse - now I can only get hot water when the heating has been running long enough for
the all the radiators to be hot.....
I pulled the cover off the microswitch , and checked for movement - the plunger does rise , but only slowly and then not far enough to trip the switch
(burner ignites and pump runs when the switch is tripped manually though )
So it looks like it will be the diaphragm - I'm just about to drain the system and get it torn down now the weather seems to have picked up a
bit
Wish me luck ? ?
Its cuz I is blond , innit
Claire xx
Will weld for food......
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