Vented to Unvented system conversion. Is this quote reasonable?

michmike

Total Including VAT: £4,675.44

Upgrade cold mains to 22mm

Removal of existing hot water cylinder and tanks

Installation of Gledhill 150 litre unvented cylinder and relevant controls / fittings and requirements

Installation of Baxi 800 system boiler - 10 year parts and labour warranty

Pressurise heating system

Install Hive smart thermostat

Run heating at maximum rate

Drain down to perform a hot flush

Re-pressurise heating

Commission and balance heating system

Register boiler with Baxi

Register boiler and cylinder with gas safe

Building compliance certificate issued in the post

Gas safety certificate issued via email

Commission and test.

Kiran

Where are you based? Also, how many people living in your property? Usual rule of thumb is tank capacity of 50L/person. If you don't have need for multiple water outlets to be running at the same time then you may be better off switching to a combi for that money.  The price looks a bit high to me, I'd get more quotes personally and compare

michmike

Thanks, Kiran. We live in Cardiff. Yes, I had my doubts about the tank capacity. Our family is 5 people big. I'm leaning towards 210 Litre one. What would you say be a fair price?

Kiran

So, a Gledhill 250L cylinder ranges in price from £500-850 online. I'm guessing your plumber is paying towards the lower end. The boiler itself and install, Id guess around the £2-2.5k. I'd look at £3-3.5k total assuming a relatively straightforward install in that area, I'm up the road in an SA postcode. It's worth getting multiple quotes though as that will tell you if market dictates higher costs. Have you also checked that you have a sufficient sized gas supply pipe?

michmike

Great, thank you! Gas supply pipe is a standard 22mm. What worries me is "Upgrade cold mains to 22mm" item. My cold mains is 15mm with the main stopock located in the downstairs toilet. Upgrading it all the way up means ripping up the walls etc, which I doubt he's actually going to do. The cold water pressure in the garden tap seems pretty good with the flow rate of 23-24 litres per minute.

Albermarle

michmike said:

Great, thank you! Gas supply pipe is a standard 22mm. What worries me is "Upgrade cold mains to 22mm" item. My cold mains is 15mm with the main stopock located in the downstairs toilet. Upgrading it all the way up means ripping up the walls etc, which I doubt he's actually going to do. The cold water pressure in the garden tap seems pretty good with the flow rate of 23-24 litres per minute.

I had something very similar done about 20 years ago. They left the existing mains supply to the kitchen and garden tap in place and the original stoptap is still under the sink. They fed the new plastic pipe up the centre/rear of the house following the path of other internal cold and hot pipes and into the cupboard containing the new cylinder and boiler. No disruption to walls at all. I presume there must be a connection somewhere downstairs, where the mains supply to the kitchen branches off the new plastic pipe.

Couple of other points worth noting:
Fitting an unvented HW cylinder is a  more complicated job than just fitting a vented one, and only some heating engineers are qualified to do it. It is a safety issue as if pressure built up too much in the cylinder it could explode. So there has to be a number of failsafe systems in place.
If I remember correctly there was a lot of work involved in redirecting/reconnecting the hot water supply pipes from where the old cylinder was to where the new one was, as it was  not in the same place.
Personally I do not think the price you have is too far out, but still worth shopping around.

FreeBear

Increasing the size of the cold water pipe only works if the incoming pipe from the stopcock is equally as large.

At a price close to £5K, I'd seriously look at installing a heat pump. Octopus are doing some very competitive quotes at the moment (have heard of well under £2K), and that would include an unvented DHW tank, new/larger radiators, and all the controls.