Can anybody suggest what might be wrong with a Potterton Statesman oil combi, its heating water but the central heating is not coming on. It works sporadically after hot water is called for in that it then stays on and gives heating for a while but then goes off and doesn't come back on again, the wall stat turns the pump 0n and off so I'm assuming that's ok(?). Diverter valve? microswitch? PCB? anything can check?
Cheers
maybe the water stat is not satisfied and thus not changing over to heating, this would cause the faults you state, check voltage on the diverter valve this will tell you if it is changing over . try and reply pete
Diverter valves for some reason look kind of 'trustworthy' and one can spend years fiddling with pump settings and bleeding rads etc before finally having a closer look at the diverter.
In fact, the ones I have taken apart all had similar semi-micro switches in them, rather like larger versions of the ones you get on mouse clickers. I am sure you will know how unreliable those are...
If you are really stingy and careful (the gearing inside is really quite clever!), new switches can be obtained for a small price from the likes of Maplins, but the mounting plastic can be rather brittle, so you may end up replacing the whole valve (driver that is: you shouldn't need to take out the whole plumbed in valve body) in the end. Still, it's worth it to get the water pumping right round the system even on the lower pump settings for a change!
S
Er, on my home planet microswitches are just about THE most reliable electro-mechanical component one encounters. I'm prepared to believed that "Pooerton" (I like it!) have obtained some unreliable ones, but generally with diverter valves it's the rubber diaphragms inside which pack up.
Then you are very lucky in not having a box full of broken mouses like the rest of us!
And the ones in the motor valve controller are about 15mm across as I recall - not very 'micro', and the contacts in them burn out just the same as all other contacts do.
S
One would think that by now a better means of doing this would have been found.
I can recall when I was a kid that the multipoint water heater would pack up religiously every 18 months and the man would come and replace the rubber diaphragm. That was forty years ago and the device was presumably something which controlled the gas flow. What do they do these days? Just operate a microswitch (in which case why not a better flow sensor?) or does it do something horrible and mechanical?
It has: current generation[*] combis have a different design of flow switch e.. turbine type instead of the diaphagm-pushing-a-microswitch type.
[*] Pooerton possibly excepted :-)
I have plenty of broken mice (the rabbit killed one: bit clean through the cable!) but it tends to be because they've got clagged up and the ball won't roll smoothly. Never had a microswitch go.
Actually diverter-valve microswitches are pretty much what's been the standard size for the last few decades (see top two examples at
In message , Steve H writes
Throw your broken mouses in the bin and get yourself one of the Logitech trackballs with the sort of dotted red ball. It's the best pointing device I've ever used.
Available for a fraction of the price of Maplins (not hard) here:-
So smooth and you can eat crisps while using it without it jamming up. :)
Listen John,
I don't know why you are determined to make me out to seem a liar when I am just relaying my own experience, but if you look at the bottom picture on your microswitch link you will see one that has been removed from its circuit board. I wonder why they did that just to take a picture? And also I am quite sure that the reason they are still making them after all these years is that they are a very reliable way for electricians to make money by replacing them when they burn out and, in the case of Potterton et al making you pay £60 quid odd for a whole new motor assembly just because they are using the same old switches for decades.
If you want to waste time draining/bleeding systems, changing pumps etc, and checking everything else before looking at the obvious well you just go right ahead. What I found wrong with our system, after several plumbers had been defeated by it, (and after twice money was wasted on new pumps) was the burned out contacts as described. I think I still have them somewhere, but I am not going to waste time finding out how to load up a picture of them into a newsgroup.
If the original questioner is still following, and this does turn out to be the cause I would recommend changing to the Honeywell driver, which, to me, seems much better thought out, and which for several years has been working as an excellent replacment for the potterton.
S
I'm not saying you're lying; just that industry wouldn't have been using microswitches for decades in everything from spacecraft through industrial process control equipment down to computer mice if they were as crap as the examples you've had. I'm not saying you haven't had some duds, just that statistically they're quite unusual. As a matter of interest how many Potterton diverter valve switches have you had that have failed, and how many mouse ones?
I don't know the circuitry of the Potterton in question but in the case of mice if a microswitch fails it's definitely not due to burn-out of the contacts, but it could be corrosion if the switch is badly designed or incorrectly selected for the application. Most non-sealed electrical switches either require a certain amount of current ("wetting current") through them to keep the contacts clean or the design of the switch must be such that the contacts wipe or rub as they're closing to cut through tarnish. Otherwise the contacts can physically close but at the low voltages of PC electronics tarnish can insulate them and they don't pass current.
They do. I've a mate who is a graphic designer and I've replaced the microswitch in his favourite Mac mouse twice.
Was it not physically clicking or clicking but the clicks not getting to the computer?
Both times the switch broke mechanically so you could 'feel' it was the problem.
And usually its the bounce that happens first and double clicks everything that is the real pain!
S
Have been using RF optimouse for some time: no wires; no balls; no need for silly mouse mats; and even the clickers haven't packed up yet! (Shhh)
S
Problem is - I'm told - that cordless mice can't be set to a high enough resolution for graphics work. If that's not so anymore I'll pass it on.
So are Macs the Dyson of computers?
Oi....
Also have graphics tablet, but use the rf mouse most of the time: even prefer using a touch pad to using a corded mouse! RF mouse can get a bit jittery if you leave it off it's station long enough for the battery to get flat but otherwise very well behaved. Have a plastic desk top work area (similar idea to the old fashioned blotter), which gives an excellent surface for this and ordinary mice to work on without any silly mouse mat edges to fall off.
S
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