Vokera Maxin 28e in Harrogate

[andyrob]

I hope this is the way to do a posting here. Sorry if not.

My daughter has just bought her first house in Harrogate and the Vokera Maxin 28e needs checking over by someone if I can't get a user manual and/or whatever else should be left with the boiler - but wasn't. Is there any recommended service engineer in the area if she needs expert help on the premises.

Specifically, although I'm 100 miles away, I'm trying to help reduce the pressure from the current 3 bar to the 1-2 indicated as correct on the guage. Firstly, I'm assuming that this happened because mains pressure is above 1-2 and the filling loop was opened too much/too long and raised the internal pressure too much. Would this be correct?

Through these forums I believe there is a red PRV somewhere at the top - is this owner friendly? Presumably the boiler front cover needs to be lifted off to gain access to this and then the PRV is turned to release pressure and then retightened.

I'm now going to search for a downloadable manual - if anyone knows exactly where these are, or can be ordered, a short reply/link would be very much appreciated.

Andy

PS Even as a GSHP devotee (with a 400% COP) I do find all this very intimidating!

 

[denso13]

Bleeding a rad will reduce the pressure

 

[Agile]

No normal GSHP would give a COP of 4 across the whole heating season unless giving a very low output temperature of say 35°C to UFH.

Its also a fallacy that its green energy when the electricity powering it is 83% generated from fosil fuels!

GSHP is about the same efficiency as a condensing gas boiler when it operates in the most ideal case.

Its also many times more expensive than a gas boiler but does have an application where gas is not available but its certainly not green in the UK.

Tony

 

[andyrob]

Thanks for the bleeding rad tip - I did wonder if that was the obvious way but wondered if the PRV (which is referred to in the excellent downloads that I found - as I hoped - on the Vokera website is preferable in some way.

But .......onto the GSHP debate, Agile (Tony).

I suppose there is plenty of discussion elsewhere but, as you said, if you have a wet UFH system, as I do, and especially if you use it for base level heat topped up with woodburner stove as required for a sitting room in the evenings (using home-produced wood and replaced with new trees to absorb the CO2 released by burning the old) then a flow of 35°C is more than enough to produce room temperatures of 22°C, especially in a well insulated house. It's often cycling between 27°C and 35°C.

With no gas option, it is indeed a great power source in certain - especially rural - situations. A big top-up of heat from the E7 tariff is taken cheaply at night, and the system is then backed off during the day. Most of the energy is coming from my field (which could alternatively be a modest garden /car-park / driveway). Heat comes in at 10-13°C for the cost of the power for the circulation pump, then concentrated in the GSHP and transferred to the UFH at whatever temperature is needed - which to be fair uses a deal more power (but from a green tariff). Up to 55°C for DHW is possible but I do tend to use E7 electricity for this, leaving the GSHP to provide just for the UFH which, incidentally, is shortly going to be heating the house and three adjacent barn-conversion cottages.

It really is worth looking at closely and for heating engineers is an interesting career-change opportunity.

Andy

 

[Nixt]

Is there any recommended service engineer in the area if she needs expert help on the premises.

There are a few ex Vokera service engineers who are now self employed as agents operating in your area. Also the Maxin is one of the most reliable combi's ever, so you should have little problem. Best call manufacturer for details of those engineers as I would assume their records are still kept.

 

[Gasguru]

The problem is GSHPs are often fitted in older properties with very poor insulation by todays standards and connected to traditionally sized radiators. The energy source is then bought at the lower standard rate tariff using very polluting gas or oil as its primary fuel source. No manufacturer has yet (to my knowledge) quoted a realistic average year round COP based on different installation types.

The gas boiler manufacturers are so dishonest they often qoute efficiencies of over 100% (achievable for brief moments in very favourable but unlikely scenarios). The government then came up with SEDBUK in an attempt to produce more realistic (if a little flawed) efficency figures.

Quoting GSHP COPs of 4 is equally well dishonest, however it is doubtful the government will force manufacturers to tell the whole story as they are now so inept when it comes to energy and it most efficient use.

Unfortunately as a career change option its a non-starter for those with a conscience, the industries full of cowboys installing GSHPs in totally unsuitable properties making wild and exaggerated claims.

I suspect the vast majority of GSHP sales are to the older generation living in very large properties having lavish lifestyles. They've been greenwashed to the point they think it will offset the half dozen holidays a year and the gas guzzlers.