potterton combi 80 locks out after a shower???????

[steve r]

hi, just found this forum and hoping someone can help me sort out a problem with my potterton combi 80 boiler.......

i had a problem with the boiler a while back where the rads would get hot when ever i had a shower, called an engineer out who diagnosed it as the diverter valve, this was changed but didn't really make any difference.

i now also have the problem of the boiler locking out, red light coming on and the boiler making a loud rumble when i finish showering, any ideas??

also my gas meter box is outside below the flue and has a black stain on the top of it, people coming to the front door have mentioned a smell of gas outside when the boiler fires up, what could cause this????

the water pressure sits at about 1bar and hot water is supplied to the taps and washing machine with no obvious problems.

any help would be great, not sure who to call/trust from the yellow pages so would like to get a few ideas before i get another engineer out to take a look.

thanks in advance

steve

 

[dave18]

You appear to have 4 problems with your system I will try and answer them one at a time.

IF YOU CAN SMELL GAS BY YOUR FRONT DOOR WHY ARE YOU WASTING TIME POSTING HERE

TURN OFF YOUR GAS AT THE METER AND PHONE TRANSCO "NOW" 0800 111 999. BEFORE YOU BECOME HOMELESS.


1, rads getting hot when having a shower, I will come back to this one.

2, boiler lockes out when shower finished, this is due to the water overheating in the boiler giving you the noises. Several things:

a, clean shower rose, water is not flowing from shower quickly enough.

b, change shower rose to one suitable for combi boiler.

c, has the boiler been serviced in living memory? heat exchanger could be sooted up, retaining heat in the heat exchanger.

d, boiler not set up correctly.

3, black deposits on meter box, see c, & d, above.

4, Smell of gas by front door: see c, & d, above.

back to 1, as the boiler is overheating this could be causing the wax actuator for the diverter valve to open the valve, so heating the radiator. or muck in your system is stopping the valve closing properly

5, Get a corgi registered engineer out to sort the boiler out BEFORE you turn the gas back on.

6, HAVE YOU PHONED TRANSCO YET?

 

[steve r]

thanks for the reply,

the smell of gas at the front door is only at the instant the boiler lights up, it's not a constant smell that would indicate a leak, if i stand by the flue when the boiler is either running or off then there is no smell of gas at all. so i guess this would indicate the boiler not being set up correctly rather than a problem transco would deal with?

the boiler was serviced a few months ago when the diverter valve was changed, the engineer used a brush to clean the heat exchanger so it should still be clean but i will check.

plenty of water flows from the shower head it has a small amount of lime scale build up on the case but the water flows from green rubber outlets so the flow of water from the head is not affected and these are easily cleaned by rubbing them. i'm sure it was suitable for a combi boiler as i replaced the old shower head when i moved into the house a few years back, i'll check when i b&q today,

i think i'll call out another corgi engineer and get him to check/set up the boiler, and possibliy drain and flush the system, the haouse is about 9 years old and the boiler has been replaced in that time, how often should the radiators be draind and flushed?

thanks

steve

 

[ChrisR]

NOt all entirely consistent symptoms maybe, but it's possible the domestic hot water flow switch is sticking after you use hot water. Rads would get hot and the boiler would overheat and cut out.

All was explained a while ago - crux is to watch for a red light on the printed circuit board - should only be ON when the hot tap is on..

see
here

 

[steve r]

thanks chris,

i'll take a look for the red light on the pcb, is it safe to run the boiler with the front panel removed?

i've got an engineer coming to take a look tommorrow, although he sounded a bit uneasy on the phone when i explained the problems, but hopefully it will get sorted,

i've printed off the info given so will let him see the suggestions that you guys have provided, also phoned the potterton technical helpline but they won't give out any technical advice unless you are corgi registered.

any idea how much a dhw flow switch should cost? (edit... just read the link provided and seen £50 quoted)

thanks

steve

 

[ChrisR]

Yes if you take the front off the outer case: two screws from underneath, pull frwards and lift off, then undo the one screw on the front which is left of centre, the lower panel folds down and you can see the pcb.

Let us know what the outcome is please.

 

[steve r]

chris,

i've taken the frony panel off and ran the hot water tap in the kitchen for a couple of minutes, turned it off and the red light stayed on, i could just see the end of the dhw flow switch body so gave it a few gentles taps with the end of my screwdriver and the micro switch clicked and the red light went out.

then decided to get a better look at it so lowered the pcb panel, i could see the microswitch and the spring that you mentioned in the linked topic,
i ran the hot tap again a few times and the swich operated correctly, i may take this off and give it a clean inside to be sure, does the whole system need to be drained to remove the DHW flow switch??

i also took a shower and the boiler didn't go into lockout, although it was a quick shower as i'm waiting on the engineer turning up.

also went round and bled all of the rads in the house, got a fair amount of air out of 2 of the upstairs rads and the gauge water pressure has now dropped, could this be linked to my problems???

will reply again when the engineer's been.

 

[steve r]

engineers just left,

he said the black stain on top of the gas box outside was nothing to worry about, if the boiler was sooting up or not burning correctly then it would shut itself down,

i think i'll clean the black stain off and see if it reappears, he suggested it could just be rainwater collecting and dripping onto the gas box,

before he arrived i had another play with the system, i waited for the central heating flow outlet pipe to cool down and then ran the hot tap in the kitchen for a couple of minutes, the central heating outflow pipe remained cold the whole time the tap was running, when i turned the tap off the CH outflow pipe became warm but not too hot to touch, i think this may have been caused by the CH water contained in the pipes that pass through the boiler moving into the system when the diverter valve opened.

typically the boiler showed no faults when the guy was looking at it, i explained how i had tapped the DHW switch and the red led on the board had gone out, so he suggested changing that and phoned for a price: £50.
as quoted by chris....

i said i'd give it a couple of days to see if the fault happened again and if it did try cleaning it before buying a new one.

anyway whilst i was writing out the cheque he continued to play with the hot tap trying to get the switch to stick and got the microswitch on the end to stick, this kept the red led on the PCB on. he gave it a tap and it free'd off then, a couple more goes and it didn't stick and then it did stick again.

the microswitch unit contains a micro switch and riveted to it a spring and follower mechanism that is operated by the DHW flow switch, this was sticking causing the microswitch to remain in the on position.

i removed the microswith unit and the operation of the spring/follower was stiff and there were signs of wear on the follower, so iv'e used some chain lube that i use on my mountain bike to lube it. it now operates more smoothly so i've re installed it to the boiler and will leave the front cover off for a while so i can monitor its operation, if it sticks again i''ll order a new one.

hopefully this will solve the problems with my system

i've tryed to explain everything as clearly as possible, hope it makes sense.

any other suggestions????

thanks

steve