Vokera Excell 80SP boiler problems

[mikeallen]

Hi All, Hope you can help.

We have a Vokera Excell 80SP Combi boiler & we are suffering from hot/cold/hot/cold water when running the hot tap for baths or showers.

The central heating fires up fine & have no problems there.

But when running the hot tap, the main flame fires up for approx 10 seconds & then switches off for approx ten seconds & then refires up hence the hot/cold water.

Could anybody give some indication as to what the problem might be as when I call an engineer out I don't want to get fobbed off with them saying it could be this or could be that & end up paying a small fortune.

Any help appreciated

Mike

[newbie1]

my guess scaled up heat exchanger/or faulty divertor valve solenoid but that is an internet opinion

[mikeallen]

my guess scaled up heat exchanger/or faulty divertor valve solenoid but that is an internet opinion

Is there a way of cleaning up the heat exchanger?

Is there a way of checking if the diaphram is working correctly as am I right in saying these can be a problem on these boilers?

Cheers
Mike

[newbie1]

yes you can powerflush system and use a descaler and yes should be able to check the operation of the divertor/solenoid but you will need someone to do this

[mikeallen]

yes you can powerflush system and use a descaler and yes should be able to check the operation of the divertor/solenoid but you will need someone to do this

Is the powerflush part something I could do myself or does this it need a corgi registered engineer?

IF so, where can you buy this powerflush stuff?

[newbie1]

powerflush isnt diy doesnt have to be gas safe engineer(corgi is finished its now gas safe)

[Puddle]

I would say the gas burners is not modulating from high to low flame .it is just going from high flame to over heat,it could be a blocked up plate heat exchanger (Is boiler making a scaled up sound like a kettle,although on this boiler you often get a slight banging sound just before boiler goes off if this is the case) but probably,thermistor faulty,gas presures on high flame set to high,these valves do need adjusting after a period of time,or hopefully not but possible fault with pcb
Other possiblity on this boiler is fan slows when heated and knock air presure switch out but this would not be every 10 secs
The boiler was a very good boiler,little work horse,but is starting to age slightly now

[mikeallen]

I would say the gas burners is not modulating from high to low flame .it is just going from high flame to over heat,it could be a blocked up plate heat exchanger (Is boiler making a scaled up sound like a kettle,although on this boiler you often get a slight banging sound just before boiler goes off if this is the case) but probably,thermistor faulty,gas presures on high flame set to high,these valves do need adjusting after a period of time,or hopefully not but possible fault with pcb
Other possiblity on this boiler is fan slows when heated and knock air presure switch out but this would not be every 10 secs
The boiler was a very good boiler,little work horse,but is starting to age slightly now

Hi, spot on. When you turn the hot tap on you see the boiler fire up & then it makes a sound like a kettle reaching high temp & then flame switches off. At about ten seconds later it fires up again & does the same thing over & over.

Any thoughts what it might be?

Many thanks
Mike

[Puddle]

That will be the main heat exchanger blocked up,plate heat exchanger will require cleaning as well,it could be a dirty system or filling loop left open,its not good news anyway I am afraid,fan will have been over heated as well

[newbie1]

if it works ok on heating mode chances are the plate heat exchanger is the culprit but the main heat exchanger will prob be as bad
you might get lucky with a powerflush and descale costs in the region of 300.00 for powerflush but more if parts need to be replaced

[mikeallen]

Am I correct in saying The heat exchanger is the part that sits above the gas flame & looks like a small car Rad? What is the plate exchanger?

can these not be changed by myself?

No way am I prepared to pay 300+ on this boiler only for it to happen again a year down the road when a new boiler will only cost a couple of hundered pounds more

[newbie1]

Am I correct in saying The heat exchanger is the part that sits above the gas flame & looks like a small car Rad? What is the plate exchanger?

can these not be changed by myself?

No way am I prepared to pay 300+ on this boiler only for it to happen again a year down the road when a new boiler will only cost a couple of hundered pounds more

a new quality boiler and fitting will cost you a lot more than 500.00

[Plouasne]

Am I correct in saying The heat exchanger is the part that sits above the gas flame & looks like a small car Rad? What is the plate exchanger?

can these not be changed by myself?

No way am I prepared to pay 300+ on this boiler only for it to happen again a year down the road when a new boiler will only cost a couple of hundered pounds more

Forgive me for saying this, but if you are asking questions like what is a plate exchanger, it sounds to me that you are not qualified to be working on the boiler, in the first place

[newbie1]

a new quality boiler and fitting will cost you a lot more than 500.00

or rather even a crap boiler and fitting will cost a lot more than that and as above no you cant change it yourself without putting yourself and others at risk

[mikeallen]

Forgive me for saying this, but if you are asking questions like what is a plate exchanger, it sounds to me that you are not qualified to be working on the boiler, in the first place

Never said I was qualified Just want to get as much information as to what might be wrong with the boiler so that when I call an engineer round to have a look at it at least I can give him the thought that He just can't fob me off with parts & labour that I just might not need.

As they say, Knowledge is power

I have already had British gas round to price for a complete new boiler system using a Vaillant ecoTEC pro28 boiler & have been qouted the best part of £3000

Thing is I can buy the same boiler for £850 & arrange an engineer myself to come & install it. Surely it's not going to cost £2150 to install it Can only be a days work tops as all the plumbing & gas pipes are there in place.