We are currently getting quotes for a pressurised boiler system. When we moved house, we noticed the water pressure in the shower was rubbish, and we might extend the house in the next few years.
Does anyone here know much about them?
I had a couple of engineers round for quotes, and I am just waiting for them to get back to us with prices. British Gas is coming out to quote today as well.
Are there any that are better? Things to watch out for?
Any advice would be helpful, as the last boiler we purchased was a combi at the old house, and this new house is looking too large for one of those.
Comments
I assume any decent engineer tested this as part of the preliminary diligence.
Get a good SYSTEM BOILER like Vaillant /Worcestor Bosch ....you don't need to pay the huge price of a Sadia Heatrae Megaflow cylinder .....only paying for name......Triton or Ariston is equally good at much lower cost ......it's only a steel drum.
Get a large cylinder.....if you have great water pressure the enhanced flow rate will drain it quickly ...no point having a great shower if it doesn't last long.
-As regards cylinders try and use a pre-plumbed cylinder.......it will save labour install costs and looks a lot neater.
Ask your engineer to calc the flow rate anticipated in terms of litres per min (this will sort men from the boys )
Whilst installing have a secondary return loop installed with a brass impellor pump ....if it's a large house this will save you waiting for taps to run hot rather than wait a minute or 2 for the hot to come through .
MOST IMPORTANT RULE ; Forget you ever heard of British Gas ......joke prices,joke labour quality,joke customer care
oh , and also very important.........forget you ever heard of British Gas !
Is your cold water pressure currently good? Your hot water will only be as powerful as your cold mains supply is in an unvented system. If that’s weak you’ll need a pump really. An existing vented, gravity fed system can be converted, how simple that is depends on the layout it’s currently in - could be a couple of days, could be a week of rearranging. You need space to fit expansion vessels if you keep the same boiler, and the pressurised hot tank would generally just replace the existing one. You will be able to get rid of the cold water F&E tank for radiators, but you’ll need external access for pressure relief valves etc which can be a headache depending on the property
I’ve had truly awful work done by a big company, Aspect. We hired them to do exactly what the OP wants, convert to unvented so we could lose the noisy pump and F&E tanks. The guy literally built a bomb in our house - installed a sealed system with no expansion vessels or pressure relief valves. It looked like a dogs dinner as well, the most shocking workmanship I’ve ever seen, I can dig some pictures out. Had to get it all redone before it blew a hole in my roof
A pressurised system requires:
-Good mains pressure (and either an accumulator or new water main if it's not)
-A new system boiler
-A pressurised stainless steel water cylinder. It doesn't need to be a megaflo though i think they have the highest efficiency. Ours is a Gledhill, I think heat loss is about 70watts on a 300 litre cylinder which isn't bad at all.
-You may need to replace some of your shower outlets
-your plumbing for radiators will need to be pressure tested and may need to be replaced
We did it when we did a major house renovation and we were putting in underfloor heating etc, but it's an expensive job
Best tanks on market are by OSO, most thermally efficient and they do models that support Heat Pump operation so that you could use that option should you need to in future OSO tanks are rated for 25 years use). These models have a much larger heating coil so you'd get quicker reheat times. If space allows, get a larger tank - min 250 ltrs capacity, again, may prove future proof for a Heat Pump centric future.
If you go "system boiler" that'll mean that the heating circuits are also pressurised. I run a standard "open vent" boiler because I didn't trust the legacy pipework in my house....much of which is buried in concrete in my place. You can have "low pressure" heating with high pressure stored hot water tank.
I've always found Vaillant to be very good. If you go down that path the Vaillant tanks integrate very nicely (you can use the thermocouple temp sensor which gives the boiler accurate information as to current tank temperature...instead of the more common U.K heating control approach from the 1950's that uses a simple on / off thermostat.
@stonevibe needs to know that you cannot use any kind of pump on a combi system
I thought I should mention that as some people are saying " Easy,get a pump "
They can now be fed by a mains boost pump now in new water regs but a pump on the other side of the boiler would simply suck the water through faster than it could heat it .