Vokera Linea hot water problem

[Deleted member 32524]

Hello,

Above boiler when shower runs cuts out at 38 deg, CH shows 90 deg when I close the filler loop. Thought partially blocked DHW. Flushed through pump head twice with chemicals, still same prob. Thought maybe primary thermistor fault? Cant get to it to test it, cant get a reading on board. No 07 code though.

What are the thoughts on Primary themistor fault or new dhw plate? Or both? Or something else?

Thanks for the help.

 

[Deleted member 32524]

Been thinking on this and Pretty sure the fan would still run if it was primary thermistor goes? Not sure though. There is a non return valve on the dhw. Would a faulty non return valve cause this problem?

Need to go tomorrow and hopefully figure this out.

 

[GrahamM]

Why is there a non return on the DHW?
Thermistors are common fault in on these. Keeps some in van. You can get a rough idea if they ok by checking the resistance.

 

[diamondgas]

Hi DuncanM .. thermisters are common ... check out bp see if its modulating ... also potential snapped spindle on hot water control knob, you may think you're turning it up but it's doing nothing I'd check modulation, check/change thermister then consider control issue before changing phex ...

 

[Deleted member 32524]

thermistors ok. modulates down. Spindle ok. The ch is now not working. lights modulates down and then shuts down cos it starts to overheat

There is a really loud rattling noise sounds like it is at the dhw plate? At the bottom right where the non return valve is. Think I am going to change it and see what happens. Never had to change one before. Has anyone else?

 

[diamondgas]

thermistors ok. modulates down. Spindle ok. The ch is now not working. lights modulates down and then shuts down cos it starts to overheat There is a really loud rattling noise sounds like it is at the dhw plate? At the bottom right where the non return valve is. Think I am going to change it and see what happens. Never had to change one before. Has anyone else?

2 screws through the flow and return brass manifilds and it falls out! Can sometimes be easier to remove if you take the gas conection pipe out between the valve and burner

 

[Deleted member 32524]

You talking about the hex? I was meaning the NRV..

 

[diamondgas]

You talking about the hex? I was meaning the NRV..

Just had to check out the mi's to see what you're talking about DuncanM ... I never realised that there was one in the flow manifold Never replaced one! In theory it should just pull out by the looks of it providing you can get to the nuts easily..!!!?

 

[Deleted member 32524]

Nuts not that accessible. There will probably be an easier way than the route I take at first and will probably see it half way through!! lol.

Hope it sorts the problem. It was working in ch but now it is also overheating. Getting new nrv and see how it goes. Probably go armed with a few bits ie new thermistors (thanks) and maybe a phex.

 

[diamondgas]

Let us know how you get on. If its effecting both hater and heating then I'd be concentrating on the area's that are common to both; flow thermister, pump,main hex/flow/return... that sort of thing.

 

[Deleted member 32524]

Fitted non return valve. Rattling noise stopped now. Still overheating. Checked flow and return service valves, both open/close. Pump ok, had head off and see it turning both sides, resistance through pump 160 ohms, so it seems ok. Now have primary hex off and soaking it for 24 hrs in chemicals. returning to fit tomorrow.

Not too much hassle to get the NRV out. Looked tighter than it was.

 

[diamondgas]

Was ther much signs of build up of muck? Hard water area? The job sounds a bit of a mare!

 

[Deleted member 32524]

Soft water. Looks not too bad with dirt??!! This is now starting to feel like the never ending job. Thank god customer is away on holiday for a fortnight!!

 

[Deleted member 32524]

Not much sign of dirt came out??!! did have it drained down when testing flow/return valves and then refilled then took off primary hex.

 

[diamondgas]

You'd need quite a restriction for it to reduce the flow to a point where it's overheating before the primary sensor kicks in and shuts the gas down! I'm a bit of a 'blower' when it comes down to checking through hex's! By the way, did you know these have a pre-heat on the hot water. They'll not kick diverter across to heating until the phex is up to temp!

 

[Deleted member 32524]

No, did not know about pre heat. Good tip. The hex is now in chemical bath and there is some amount of blackness in the water now. If this does not work I will be pulling my hair out!!

If this does not work I can only think of fault on the pump head. Maybe worn bearings.

 

[Deleted member 32524]

Took hex out of chemical bath there and it has not produced much dirt at all. I can blow through it no problem. Do not think that this is the problem now with the little amount of cr=p that came out.

Ahhhh!!

Going back now to refit hex and see if it has helped at all. My feeling is it will probably still do it.

 

[Ermintrude]

Took hex out of chemical bath there and it has not produced much dirt at all. I can blow through it no problem. Do not think that this is the problem now with the little amount of cr=p that came out.

Ahhhh!!

Going back now to refit hex and see if it has helped at all. My feeling is it will probably still do it.

Needs to be ultrasonic bath to remove deposits effectively.,

 

[Deleted member 32524]

ultrasonic? How do I do this?

 

[GrahamM]

What did you try to clean with?
Never used it but spirit of salts has been said to give good results.
An ultrasonic bath can bring them up almost as good as new but you need access to one.

You sure the divertor assembly is operating ok? Had to replace few bobbins due to sticking. There is a kit for this.

 

[Deleted member 32524]

Great suggestion. I like it. I have been down the circulation problem route. Only had a quick look.

It makes sense now I have thought about it. Are the kits easy to fit?

 

[Ermintrude]

What did you try to clean with?
Never used it but spirit of salts has been said to give good results.
An ultrasonic bath can bring them up almost as good as new but you need access to one.

You sure the divertor assembly is operating ok? Had to replace few bobbins due to sticking. There is a kit for this.

Dish washer salt in ultrasonic bath leaves u thinking a soap bomb went off but the plates are immaculate. Cherry cola does a good job when left for 5 hours

 

[solutions]

Dish washer salt in ultrasonic bath leaves u thinking a soap bomb went off but the plates are immaculate. Cherry cola does a good job when left for 5 hours

Does it have to be cherry or will regular cola do? ?

 

[Ermintrude]

Cherry has higher acidity

 

[mfgs]

Sounds like a diverter issue to me. If its overheating on both, then it isn't getting rid of the heat effectively.