vaillant sine 18

[kev_1911]

help and advice needed please,changed the flow switch assembly(complete)on this boiler yesterday all ok on leaving,however customer rang back today boiler wont switch off even when the clock/programmer is off,went back to it and indeed it would'nt shut down.got the burner to shut off briefly by turning the stat down to 1 but the pump kept running till the burners came in again,seems ok in water only mode will start up and shutdown ok prob only when in htng mode,checked microswitches(the ones i could get to,they were ok,isolated clock- burners still lit up though......any please.

 

[kev_1911]

ok vaillant are saying that the main switchboard has prob packed up,however they say its not conclusive and it could be other things,my concern is that this old couple have thrown £200 at this boiler already and a new board is close on £100 plus fitting and if that does'nt cure it then thats even more £'sssss,wonder if i should be asking them consider a new boiler or go along with the line of repair at all cost???

 

[DP]

Kev if you are an RGI, I would suggest you follow the MIs to locate part of circuit causing a permanent demand. Cannot see how Vaillant are going to be of any assistance for this type of fault.

Get a meter and work backwards until you find the contact causing the problem. Remember, this boiler (before others made this facility available) has preheat. Have you checked this is in order? Have you removed the link from the 'stat/ timer' terminals.

 

[kev_1911]

DP hi thanks for reply,yes i am a rgi mate although a fairly new 1,so my experiance is limited,anyway i did isolate the clock/timer but the boiler still fired up,vaillant told me yesterday that if the microswitches are ok then it can only be the board? but this morning they are saying it could be other things as well, and the pre-heat is ok(set to off)even when the burner shuts down the pump still runs? this machine is 21 yrs old by the way.

 

[namsag]

On the water section (centre bottom of boiler) make sure pin is retracting back fully and not staying out and operating the microswitch so boiler thinks there is a HW demand so staying on

 

[kev_1911]

namsag hi thanks for that i will check it when i return to the boiler,is it visable from underneath the boiler or do i need to remove the alli cover from the front(switchbox cover)? also by the way it seems to be working fine in hw mode,its just the c h thats giving probs,could well be somthing sticking as flame goes from full to low constantly when htng is on?

 

[Gasguru]

Remove front cover. Check pin is not siezed in gland and switch is adjusted.

 

[kev_1911]

Gasguru hi,cheers for the info,i will look at it,great pic by the way,i take it the pin moves up and down yes? and will the boiler run with the cover off? cheers.

 

[Gasguru]

Yes the pin should move up and down in response to a hot water demand.

You can just prise the front cover forward sufficient to see the pin moving.

 

[kev_1911]

Gasguru thanks for reply,i assume the pin to be free as this boiler is working fine in hw mode,if i swith the left hand rocker to 0(water only) the boiler works as it should,however my probs start when in heating mode,it wont shut down even with clock/programmer turned off at the wall it still runs? customer is now thinking new boiler,but after spending £200+ on the flow switch i feel it might be worth trying to sort it,but given its now 21 yrs old am not sure if its right to carry on with repairs what do you think please?

 

[Agile]

customer is now thinking new boiler,but after spending £200+ on the flow switch i feel it might be worth trying to sort it,but given its now 21 yrs old am not sure if its right to carry on with repairs what do you think please?

I dont know what kind of flow switch would cost £200 or even why anyone needed to change one!

This is a solidly built boiler and totally repairable by anyone who understands them.

Have you checked that the diverter valve is moving freely and that its microswitchs are operating correctly?

Tony

 

[namsag]

Agile you should know This boiler doesn`t have a divertor, it has a water section and a FLOW SWITCH which is located on lefthand side about 12 inches long connected to primary and water to water heat exchanger that contains wax capsule etc etc and do cost in the region of £150 quid plus.

 

[kev_1911]

thanks namsag,vaillant in their infinite wisdom decided to make the wax capsule obselete so your forced to buy the whole flow switch complete with micro's up top,the origonal fault on this boiler was actually the wax capsule wich i managed to get hold of 1 my supplier had on his shelf but when i installed it i could'nt get the damm thing to seal so i had to buy the the whole switch @ £149.70 plus fitting, well ripped off!!! the wax caps are only £30....... kev.

 

[Agile]

Agile you should know This boiler doesn`t have a divertor,

Regardless of what Vaillant choose to call it in their Germanic English, the function of the unit with the wax element is to divert the system flow from the heating circuit to the secondary heat exchanger.

The wax element comes with a wide flat washer and a thin one if I remember correctly.

I think its the flat one which creates the seal to the outside?

Tony.