Nightmare System !!! - Vokera Compact 28

[bigdev10]

Evening all,

I was wondering if anyone out there would be able to help me with a few issues that I have encountered over the past wee while.
A bit of background first... System 4 years old from new (new build Barratt home), bottom flat on single level. Vokera Compact 28 Combi with Copper pipes. Pipes look to go up into roof then down to rads (no hatches to confirm). No vent v/v according to Barrrats due to being a pressurised system.

Biggie at the moment is a significant drop of temperature in several radiators, mainly bedrooms. Started as loud gurgling/pops/crackling in boiler. Had gas man in the other day who successfully left me with ZERO heat in any rads (and still charged me...).
Have since managed to chase all the air out of the system in order to get me back where I started. DHW ok (apart from issues of hot,cold,hot, cold which has been a pain in the backside since day 1), albeit boiling when first turned on immediately after central heating demand.
Central heating loop through heat exchanger now sounds to be boiling up and goes roasting. Return pipe only ever slightly warm, whereas supply melting hot. CH doesnt stay on very long as supply doesn't seem to travel, therefore doesn't dissipate, which in turn leads to rads not geting a lot of heat. Rads closest to start of main loop are as hot as normal, but the rads furthest don't heat up at all. Have shut all rads off, with room rad on only, but still only gets 'warm'. Pump and impeler look ok, and definately running but possibly not enough oomph (on top setting). System has been bled and charged, single rads have been bled/charged. Have cracked the thermistor fitting to vent air from boiler (again, no vent up high) as well as blowing out boiler, etc.

Any thoughts on whether it's the pump or not? Possibly sludge? Supposedly got a manifold somewhere that might be blocked? Pressure holding ok, only 4 years old and live in soft water area.
Cant seem to find any documentation on the boiler (unsure if Vokera support any longer) and diverter looks a bit 'old school' for being a relatively new system (not a CH engineer, but looked at Vokera's newer models and looks motorised, as opposed to pressure valve operated).

Bit of a long winded history there, but really struggling. Got a wee one on the way and could do with getting this sorted, but without the grand costs. Any help or info would be greatly, greatly appreciated...

Many thanks,

Ryan.

 

[Fellacim]

If the pipes rise above the boiler, they need automatic air vents (aav's) or at least little manual ones in them. Sounds very much like air problems.

 

[bigdev10]

It looks like it has an AAV (well accorsing to the manuals for a Compact 29). Unsure if this is knackered, but heard a few pops from it the other night once I managed to chase air out of system.

 

[Fellacim]

The boiler will have one but the pipework rising above it also need it.

 

[bigdev10]

Spoke to Barrats, who spoke to the plumber who installed the system (supposedly...) and he said that no vents were installed in the piping, as being presurised, should be able to force air out of drain point for system on rad at front door. Struggling to see why this may be, always thought a vent should be fitted to highest point in system?? Thought might be a v/v in upstairs neighbours house possibly, but ensured by Barrats this would not be the case...

 

[Fellacim]

Its good practice to install vents at high points. A lot of the time air can be forced through but it depends on how well the pipework has been done. If youre still hearing air then it proves that its still in your system. Air can cause huge problems in central heating systems.

 

[bigdev10]

Many thanks for the responses,

Air noises seem to have settled down, but symptoms still point in that direction though. Just seems to struggle to pump round the absolutely boiling water in the supply side. House has always been hot, hot, hot even in last years cold snap, but a recent change has taken place over last month or so.

 

[studips]

it can be a tiny amount of air that causes a blockage, have a chat with barratts and see if they can get it sorted as good will.

had this recently and just slackened off the return union nut at the boiler - a little air bled out and the heat started moving within seconds - it was that simple.

at 4 years old, that system should still be quite clean.

if the pump is pushing against an airlock, it isn't the pumps fault.

 

[bigdev10]

Will give that a bash. Should I try cracking every fitting I have access to and see what happens? Just find it bizarre how it has started happening, with no lead up symptoms? Maybe been like this for a while, but only noticing now into the winter months...
Whole system been brutal since install. Noisiest I have ever came across, whole boiler rattles (mainly through poor fixture to wall, poor sound insulation), loud woosh when igniting, etc. Dunno if it's just cause I have a grudge against it that I notice every peep out of it, gas man didnt think was that bad, but when you and your missus gets woken up in middle of night with a loud WOOMPH, you know there's problems...

 

[Agile]

The system is four years old but how many times have you had it professionally serviced?

You talk of a gas man coming and apparently leaving it worse that when he arrived.

What did he say about it and why did you pay him? What did he propose to sort it out?

Tony

 

[Groovejet]

Was the system chemically cleaned after installation(Sentel or Fernox)?
And was inhibitor added to protect corrosion ?.
Do u live in a hard water area?

 

[bigdev10]

Unsure if was cleaned, but believe inhibiter had been used (fluid drained from system was greenish in colour and smelled of chemical). As for gas man, he is a local guy who was round before. Had feeling I knew more about it than he did (maintenance engineer to trade, have worked on many pump/heat exchangers in past but not domestic stuff). To be fair, he and his pal gave it a bash for over 2 hours and maybe pointed me in the right direction to try and sort myself. Only took 45 quid. Said he would be back, but not seen him since (hence why on here).