I am hoping to move to a house which currently is heated by storage heaters. I will probably want to have central heating installed, oil fired - there is no gas in the area. When I had a new boiler fitted at a previous home, a bungalow, the CH side was pressurised. It worked brilliantly as the previously luke warm radiators in the attic room suddenly became as hot as the other radiators and were no longer air traps. The HW was fed from a storage tank in the loft, pressure was OK downstairs but there was a monsoon pump fitted to supply the upstairs bathroom. What are the group's views on a new system fitted from scratch, in this case in a 2 storey house with a loft that could contain a storage tank. Don't know anything about water pressure in the house yet. But starting from scratch my options are pretty open, subject to any national/local regulations.
Pressurised Hot Water/CH Systems
Aug 29, 2010
19 Replies
That gives the impression of a poorly designed system that was drawing air into the system. The new boiler set up probably cured that problem.
You could start here
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that avoids a pump for the bathroom water is good:-)
You're dead right there! When bleeding that rad I took the brass core out and put my finger over the hole, nearly got sucked into the radiator.
That's interesting, thanks :-)
Another good starting place:
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sealed (i.e. pressurised primary) systems are preferable to vented system with header tanks. For hot water you need to assess your requirements. For moderate usage you may be happy with a combi ("instantaneous" heating of hot water and no storage), for higher volumes and flow rates an unvented cylinder or a thermal store may be better.
If a thermal store appeals then there's lots of info here:
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is the way ahead: Mains pressure HW, no header tank, flexible with heat sources (any combination of boiler, solar, ground source, immersion, solid fuel).
I installed one last year. One day when I build my "grand design" it will have one as well.
They do look interesting. Can they really supply enough "on demand" hot water to fill a bath?
No problem at all. In fact multiple baths.
The store typically sits at circa 70C. The boiler fills the store directly from the top downwards and is set up for 75C "flow". Recovery is very rapid indeed (I have a 28kW boiler)
Solar is indirect by the way (antifreeze is expensive).
These stores also make for a very elegant solution with UFH....which my as yet undesigned "grand design" will have
Mains pressure hot water round here would be a nightmare. It would take forever to fill a bath.
I have a reverse nightmare. 10.8 bar rising main.
I use a regulator to take this to about 2 bar, which makes things somewhat less alarming when you fill the kettle.....also stops the garden hose fittings constantly shooting off.
Dunno, but a simple pressurised tank can, and they are cheaper. Not sure what the difference is really.
It couldn't take longer than a header tank, because if there wasnt pressure to fill the header tank, you would have no water at all
So mains pressure will ALWAYS be higher than header tank pressure.
Only time a tank makes sense is when the actual flow rate of the mains is pathetic. But that's something to take up with the water company.
It's only actual flow rates that matter in practice.
Adequate is their response.
I konw that the cost is not everything, but I'd carefully work out how long it will take to recover the installation and running costs of the oil fired system. It could be that electric is actually best.
Robert
Fair comment, Robert. I'm in the limbo you always end up in buying a house in England and using the time to think & plan :-)
With a heat pump, its cost competitive right now with oil or gas but oh! the installation costs...
presume you refer to the "slinkies in the vast trenches" collector pipes? what happened to the "single borehole" approach?
Jim K
Even MORE expensive!
And the heatpumps are horrendously priced, too. Cashing in on eco bollox.
AND you have to design the whole plumbing round them. No small bore high temp stuff here. Its all lots of quite warm water, not a little bloody hot water!
So UFH, bigger rads, and booster immersion heaters for the tank..and THAT has to have a far larger heating coil rear to work off the warmish water.
Or use a heatbank in between.
Heat pumps do, of course, include air conditioning. I'm not sure how sunken pipe systems rate, but air conditioning equipment definitely gets you brownie points in energy efficiency surveys.
Colin Bignell
On 2010-09-01, Nightjar
No, mostly they dont.
Those cost EVEN MORE!!!
I'm not sure how
Cant imagine why.
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