unvented cylinder

[retyfraser]

I have recently received a quote to replace my gravity fed system with an unvented cylinder. I have a quote for £2,150 and is this reasonable ? ( including pipeworks , cylinder, power flush dtc.,)
I have a 4 bed with 2 baths. He also said a 170lt should be fine ( we are 4 people at home and very rarely we would have 1 or 2 additional folks)

Is the cylinder size sufficient ? and the quote ? This is the first time i am doing it and just want some advice, thanks

[Villagernumber9]

The price all depends on the make and model of the cylinder.
They can cost from as little as £350 for a 170 litre cylinder.
I would certainly get a few more quotes first before deciding.

[Villagernumber9]

Also, think that you would be better with a 210-250 litre cylinder for a 4 bed, 2 bath house.

[retyfraser]

Thanks a lot. The other hurdle is my mains water pressure is around 17 - 18lt /min. Is that a blocker?

[PigletJohn]

18lpm is OK. Run a 22mm pipe all the way from the stopcock to the cylinder, and the cylinder to the hot bath taps, to get the best possible flow. Use full-bore valves on the pipes, not little 15mm ball valves which are a bit constricting.

A bath takes about 100 litres (less if you are fat) and the boiler will be a bit more economical on gas if you time it to run once or twice a day, rather than topping up every time you fill the sink. So 200-300litres are popular sizes.

However if the boiler is fairly modern, by the time you have had a bath, hot out, towelled dry and cut your toenails, it will have reheated the cylinder, so if you want four baths one after the other, it will do it, you just need the boiler timer set "HW on" around bathtime.

An unvented cylinder can give a very powerful shower, and people will be tempted to use a lot of water.

[Villagernumber9]

Pretty much what piglet John said. Water pressure will only really effect a combi boiler.

[Whatdoiknow31]

No, you need good flow rate at the cold mains for combination boilers AND unvented cylinders. You ideally need 20lpm for an Unvented cylinder - if you haven't got that then an Accumulator can be installed.

£2000 seams a lot, but I don't know exactly what work they have specified. What make of cylinder, length of pipework involved (if you are having in new position to existing vented cylinder) whether they are putting balanced cold feeds into your existing bathrooms etc. They maybe upgrading controls to a Splan within that price. Can you list what is included, I would be able to advise more (area differences allowed of course)

Whoever you get to do it make sure they have the G3 qualification to sign off with Building Control and install a Lime Scale reducer onto the cold feed to the cylinder (unless you have a water softener)

[retyfraser]

Hi, Thanks a lot Whatdoiknow31 . I thought I need just a gas safe , but i need a Gas safe and G3 guy ?

So, the quote is £2,135 and includes :

170l cylinder
Expansion Kit
All pipework and fitting
Magnetic Filter
Powerflush of system
Run overflow pipe under floorboard
Landlord Safety certificate
Removal of overhead water tank from loft

[Whatdoiknow31]

Bit confused.

Is your current boiler a regular boiler from an open vented system (you have two tanks in your loft, one for your hot water cylinder and one for your heating system?)

Unvented cylinders come with expansion vessels, either internal or external so I would not expect to see that listed on a quotation separately. Also the magnetic cleaner is not required, or power flush on a unvented cylinder installation.

From what you have listed it sounds like the are quoting to convert your heating system to a pressurised system (expansion vessel) putting a magnetic cleaner on the return to the boiler (which protects the boiler from any muck in the heating system) and doing a power flush. As well as changing your hot water cylinder to an unvented cylinder. Does this sound like what you have asked to have done?

My only concern is that there is no mention of balanced feeds to the bathrooms, this may not be possible as it would involve lifting carpets and floorboards. And most importantly no Lime Scale reducer on the cold feed to the unvented - you will need a 22mm one as a 15mm will restrict the flow too much.

Did they test your incoming cold mains to make sure you have enough flow?

Also is the property rented out? Don't understand why they have included a Land Lord Certificate if it's not.

You can check their qualifications on Gas Safe to make sure they are qualified for Unvented Cylinders - it's a totally different qualification to Gas and not a lot of engineers have it by comparison.
You need gas safe to work on gas appliances and G3 to work on Unvented. If they have G3 they would normally have Gas

If they have quoted for all the above the price sounds about right (depending on make of cylinder of course) just check their qualification and water flow rate. Always good to get max three quotes as well ;-)