Vokera 20-80 Flowmatic Boiler - Low Heating Pressure

[Chief1]

Appreciate any assistance with heating system pressure loss on a Vokera 20-80 Flowmatic.

I keep topping up the pressure via the fill loop but the pressure constantly drops to approx 0.5bar within approx 1hr.

I have also been bleeding my top radiator to release air.

Also this means when we open the hot tap the boiler makes a bang and a clang as it starts up to heat the hot water.

Have checked as many heating pipes and connections as I can find including underfloors but cannot see any pipe leaks on the system.

Is it possible that there is an issue in the boiler itself?

Cheers

 

[lightning]

Check outside to see if the blow off pipe is dripping????

 

[Boilerman2]

If the pressure is dropping then you HAVE got a leak, it could be on the boiler - Saftey Valve dischage, due to faulty valve or deflated Expansion Vessel, (most likely especially if the boiler has not had a PROPER service lately - which would include a check of the expansion vessel pre-charge!)

 

[nickso]

heat exchanger is a common leak on these.

 

[DP]

HE union seals me thinks, and stuck flow spindle good possibility.

Nicso, do come across occassional leaking HEs on flowmatics and excels but not as often as those fitted in Lineas. Linea ones are paper thin

 

[Agile]

Only a registered gas engineer should be checking the main heat exchanger.

However, after topping up the pressure to 1.5 Bar and then closing the heating isolating valves underneath will show if the leak is in the boiler or the radiator system.

Tony

 

[nickso]

do not close the isolation valves. they will leak.

 

[nickso]

HE union seals me thinks, and stuck flow spindle good possibility.

Nicso, do come across occassional leaking HEs on flowmatics and excels but not as often as those fitted in Lineas. Linea ones are paper thin

are they different danny? i thought they were the same material and construction with slight differences for size etc?

i've not cut them open to investigate though.

 

[Agile]

The iso valves may leak but currently he has a bad leak and all his efforts have not found any cause.

Closing them to discover which part the leak is in is really his only option if he does not want to call a professional yet.

If the leak is on the system then he may be able to fix that as a DIY job.

Tony

 

[nickso]

disagree.

all he needs to do is have a peek in the boiler to confirm the leak is on the system.

closing the isolation vavles on these is a last resort and you really need to mention the likelyhood of leaks when recommending stuff like that.

 

[Agile]

We are not permitted to advise non gas registered people on here to do any "gas" work like opening the combustion chamber.

The appropriate advice if he does not want to take the risk of closing the iso valves would be to call an RGI.

Whilst I am careful and avoid closing some iso valves, even if they leak very slightly at first they usually stop after a few days. I only change perhaps 2-3 a year.

Tony

 

[nickso]

you don't see as many boilers as you make us believe you do then, as i change that many in a month. vokera ones are particularly bad for it and do not magically re-seal themselves in most cases.

i am permitted to advise anything i bloody like. removing eight screws and a panel on a flowmatic will result in two things. first he may find a leak. second he may notice the case seal has gone hard at the bottom. thats it. it will not result in the end of the known universe.

The appropriate advice if he does not want to take the risk of closing the iso valves would be to call an RGI.

if thats the appropiate advice why the hell didn't you advise him of it in the first place?

 

[DP]

OP, do not isolate the valve on two pipes, under the boiler, under the boiler to the left.

Feel the case about a third from the top. If hot, I would suggest you get the boiler serviced as stated in the manual.

If you have been suitably medicated, have a peek inside as Nicso says. You will get the measure of neglect that your boiler may have suffered due to lack of proper TLC.

In my estimation, this boiler is unbreakable if looked after.

Nicso, Flowmatic and Excel main HE are the same. almost certain Maxine is same. Linea have thermister near the outlet tapping. Weight is fraction of what was fitted to aformentioned models. The HWHE on Linea also prone to leaking if mains pressure is good. Have replaced a few.

OP, do come back and post findings.

 

[nickso]

Please note rule 10 (Posts covering DIY gas work are not allowed.) - See here for the forum rules.
Opening a combustion chamber is really a step too far. It would be more dangerous on some other boilers.

if it was a "more dangerous" boiler i wouldn't have suggested it.