Odd reset problem with a Potterton profile 100e

[discostewart]

Hi,

I have a SIME badged Potterton profile 100e.

Every morning as my electronic Programmer switches off the boiler therm stat reset button trips and i have to go down and reset it. (The button under the boiler). It basically does it aswell with +1hr or turning the water off manually,

We have replaced the overheat stat and the pump over run stat. We also found the gas supply has been set to the wrong flow and altered it. Neither over these things has changed the problem. The ONLY thing that alters is it very odd. If you change the stat on the hot water cylinder in the bathroom down to 50 it doesnt reset! Im not sure why altering the temp of cylinder would affect the boiler.

it does not reset on the central heating.

Am at a total loss as r two corgi guys helping me.
;(
Stewart

 

[sonray ltd]

change the cyl stat.

 

[plumberdate]

is there a motorised valve on the sytem? may look sumert like this??

Motorised Valves - DIYWiki

 

[discostewart]

Plumberdate:
there are what appears to be two motorised valves

honeywel f4 9933
honeywell f9 9923
both in airing cupboard.
system is fully pumped.

Sonray Ltd:
happy to change cylinder stat but why would that cause the boiler to manually reset downstairs ?

Im a layman so excuse my question but the temp of the cylinder shouldnt overheat the boiler ? Its trippng at the end of the cycle not during ? (ie when the boiler turns off as HW goes off at end of programme). This morning however it didn't cut off because last night i altered the stat down from 65 to 60. Which kind of fixes it but only in a bodge sense and i want to sort it properly. My corgi guy doesn't seem to think it would be the stat/valve.

 

[plumberdate]

hiya, it could be soo many things without being ther its hard to tell.

beings as when u mess with the cylinder stat, seems to point to some sort of overheating. if one of the motorised valves has broke it could be that the hot water is over heating as both hot water and heating will be on at the same time (when you select central heating on programmer - does hw come on aswell)

hard to tell, but its looking like overheating from the info supplied so far

 

[discostewart]

The hot water button doesn't come on the programmer when your CH does. And i would say it isn't heating both at same time as water cold in evening when CH is on and HW program is off. But i will check that tonight.

I agree its overheating but could a cylinder stat cause that ? the overheat stat and pump overun stat have been changed to no affect.

 

[Deleted member 2053]

If you have two motorised valves do you also have a bypass? If both valves shut with no bypass then there is nowhere for the pump overrun to pump to and the residual heat in the heat exchanger could be enough to trip the overheat. It is just possible then that reducing the cyl stat will reduce the return temp so the residual heat does not raise the water enough to hit the overheat. Easy to test - just hold one of the motorised valves open very slightly (not enough to activate the microswitch) as you turn the power off. If it doesn't trip then you have your answer.

 

[discostewart]

there does indeed to appear to be a bypass. the only odd behaviour we can find is the pump override. it seems to kick in on the central heating most of the time but not with the hot water. ie it only runs after central heating has shut down. bypass appears open, pump operational so not sure why its intermittent, as the signal should be either on or off.

 

[Deleted member 2053]

Well that would certainly fit a little better with the fact that you can stop the overheat with the cyl stat. Start by unclipping the programmer from the wall and then check that you really do have a permanent live to the boiler.
This is a long shot but I did once come across a situation with a profile where someone had rewired the boiler internally because he couldn't work out how to correct his faulty exteral wiring. That coupled with some external wiring error would give you this result. I know much better plumbers than I who are the most appalling electricians. Profiles always used to have a colour coded wiring diagram on the inside of the undertray.

 

[discostewart]

Plumber has checked permanent live is there. Another plumber verified it. Also the fact the pump overides when central heating shuts down would suggest something is in place?

do u think changing the cylinder stat would have any bearing on this? i dont understand how it would ?

 

[Deleted member 2053]

No I think you would be wasting your money. This has all the hallmarks of a wiring fault. I would like to know under what conditions the permanent live was checked. It is only of any value if the programmer is disconnected at the time - hence my suggestion that it be unclipped from the wall. What part of the world are you in?

 

[discostewart]

i live in folkestone in kent.
I noticed something odd the other day. If u switch the pump down from 3 to 2 then the boiler resets whilst heating within a few hours. i.e. I dont think its pulling the water away quick enuff. Also the plinth heater in kitchen will only come on intermittently. Could my pump be the issue? It did have a problem of too much air passing thru it for ages due to a piping issue thats been fixed.

 

[Deleted member 2053]

If the pump was the problem I would expect the heating to cause the lockout rather than the hot water. Still it won't hurt to take the top off and have a look!

 

[mcmoby69]

if i have read the posts correctly the pump overrun works on ch but not hot water. could it be that when the cylinder stat reaches temp it cuts the supply to the motorised valve which in turn cuts the supply to the pump?
this will let latent heat in the exchanger continue heating the water in the boiler taking it overlimit. if the cylinder stat is lowered then it drops the temperature at the boiler before it gets to overheat temp. the cylinder stat only needs to be set about 60 degrees anyway. without looking at it personally it is a bit of guess work! hope it helps even if it does just rule something out

 

[discostewart]

Well the boiler is now behaving itself

we:
changed pump over run stat and nothing happened.
changed pcr on boiler and boiler stat and now it seems happy.

was abit of guesswork and not reallysure hwat solved it.

 

[ashtrans]

Hi,

I have exactly this problem,

I got to the last post and it says the PCR may be the problem,

next question is, whats a PCR ?

Dave

 

[discostewart]

- PCR is the electronic board that runs the boiler, if u take off the bottom hood you can seeit on the right. You can pick up cheap refurbished boards from ebay just put in the part number (407677): Here is one:
Potterton Profile / Prima 30-100 PCB 407677 on eBay, also, Water Heaters Boilers, Heating Cooling Air, Home Garden (end time 18-Mar-09 08:37:16 GMT)
PCB is about 30 pounds but ring the company and pay by card insteadof buying from their ebay site. (Otherwise you have to send old board in to get the deal).

The other parts it can be are about 15pounds each and are:
Boiler stat 907724
overheat stat 404506
pump overrun 404505

You can pick up all the parts cheaper yourself, i use sabre systems on ebay, again just type in the part numbers.

Then get a corgi guy to change all of them. Its honestly cheaper in the longrun than getting a corgi guy back three times.

 

[ashtrans]

- PCR is the electronic board that runs the boiler, if u take off the bottom hood you can seeit on the right. You can pick up cheap refurbished boards from ebay just put in the part number (407677): Here is one:
[DLMURL="http://www.ukplumbersforums.co.uk/redirector.php?url=http%3A%2F%2Fcgi.ebay.co.uk%2FPotterton-Profile-Prima-30-100-PCB-407677_W0QQitemZ260363288216QQcmdZViewItemQQptZUK_Home_Garden_Hearing_Cooling_Air%3Fhash%3Ditem260363288216%26_trksid%3Dp3286.c0.m14%26_trkparms%3D72%253A1683%257C66%253A2%257C65%253A12%257C39%253A1%257C240%253A1318"]Potterton Profile / Prima 30-100 PCB 407677 on eBay, also, Water Heaters Boilers, Heating Cooling Air, Home Garden (end time 18-Mar-09 08:37:16 GMT)[/DLMURL]
PCB is about 30 pounds but ring the company and pay by card insteadof buying from their ebay site. (Otherwise you have to send old board in to get the deal).

The other parts it can be are about 15pounds each and are:
Boiler stat 907724
overheat stat 404506
pump overrun 404505

You can pick up all the parts cheaper yourself, i use sabre systems on ebay, again just type in the part numbers.

Then get a corgi guy to change all of them. Its honestly cheaper in the longrun than getting a corgi guy back three times.

many thanks for your help,

much appreciated,

Dave