What's involved in an unvented system service?

I'm due to have my boiler serviced next month and I'll need the unvented system serviced at the same time. What's involved with servicing it and is it likely that a Gas safe man will be able to do both at the same time or am I likely to need two different engineers? I know the unvented will need a G3 bloke but is it common that most gas safe engineers are also G3 certified too? What do they actually service on an unvented system? (the unvented system is about 2 1/2 years old now and never been serviced) I know, I know.....

A lot of RGIs carry the G3 unvented qualification. Many will also register their qualification with Gas Safe and you will see “Unvented Hot Water Storage Cylinders” ticked on the qualification list on the company/engineer verification screen.

As for what it involves, this depends on the cylinder (Manufacturer instructions will specify the required maintenance). Most of the time it is a visual condition assessment of the cylinder, validation that the TPRV discharged and reseals (Most of the time it won’t unless it’s been regularly operated and even then will often need replacement), checking or repressurising the expansion tank or resetting the bubble (Megaflo’s). Some will then need draining and descaling or anodes replacing which can also get expensive.

I’ll be honest and say that I can count with my fingers the amount of times I have been asked to do a domestic unvented service in the 18yrs I have been registered. Most people wait until they fail and we do a proper “reset” of the cylinder with a raised eyebrow when we issue the price. Not that I condone this behaviour, it’s just the way it is.

Off the top of my head ....... check pressure reducing valve pressure, check air gap or expansion charge, test safety valves work and reseat, check discharge pipework is safe and visible, check operation of controls, check temp of hot water, check flow rates etc...

Can take a while to test everything especially if the install is poor.

Ok thanks. Had a quote from a local firm today (they installed the unvented system a few years ago but not the boiler Vaillant Ecotec plus 418 which was fitted just under a year ago). £80 for the boiler service, £84 for the unvented system service. Both prices plus vat. Does that seem about right?

Alittle high for my area.

BigSnoopy01 said:

Off the top of my head ....... check pressure reducing valve pressure, check air gap or expansion charge, test safety valves work and reseat, check discharge pipework is safe and visible, check operation of controls, check temp of hot water, check flow rates etc...

Can take a while to test everything especially if the install is poor.

Click to expand...

To add - clean pressure reducing valve strainer.

I'd be £70+vat for the boiler service and £50+vat for the cylinder service, assuming both are done on the same visit and no spares are required