Advice: new CH system

I'm having a new CH/HW system installed from scratch (to replace a somewhat antique, expensive and broken warm air/gravity system). Our chosen plumber has recommended:
Vaillant Ecotec 630 condensing boiler Santon Premier Plus unvented pressurized cylinder 15 radiators for a 5-bed house.
He seems to be competent, but any comments would be appreciated. Is mains pressure HW the way to go? (We already have a CW tank in the loft, which would go.)
I am particularly interested in the safety and servicing requirements of unvented systems. http://www.gasapplianceguide.co.uk/Mains_Pressure_Hot_Water_Systems.htm gives warnings, but is it partisan?
We already have a shower pump fitted in one of the bathrooms. Is this permitted under the bye-law that prevents pumping from mains pressure systems, or does that only apply to combi systems?
thanks, Andrew.
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Andrew Haylett wrote:

Mains pressure is good *if* your mains pressure and flow are adequate, and - of growing concern in some areas - you are confident about the continuity of the main supply. If mains pressure/flow is not adequate, stay away from mains pressure systems.
For a 5-bed house, is he just going to fit TRVs to all rads, as for that size of house some multiple zoning of rads could be useful.

There are alternatives, such as thermal stores / heat banks, which can provide mains pressure water but do not use a pressurised store, if this is a concern.
This does not affect the choice of a pressurised primary (radiator) circuit, which is usually recommended.

AIUI pump (a) shouldn't be needed, and (b) would have to go.
Owain
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He can always install an accumulator which gives mains pressure hot water in volume. One can be rigged up quite cheaply.

Yep. And each zone can go directly back to the heat bank cylinder which is a wonderful neutral point and CH buffer. Each zone with a Grundfos Alpha pump, TRVs on all rads and simple single stage time clock. A weather compensator can be used to float the temperature of the CH buffer in the store in line with the outside temperature promoting condensing efficiency. I would use a Glow Worm HXi boiler which is simple and made by Vaillant and cheaper too. Also have two cylinder stats to eliminate boiler cycling.
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Given the space..... Unfortunately water, in the liquid phase, is not all that compressible.
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Matt, you need to put one in, to get rid of all those pumps.
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Good boiler.

Bzzzt. Wrong. This what they can do. http://www.waterheaterblast.com
Tell him to fit an integrated heat bank (thermal store with a plate heat exchanger). This will outperform the unvented cylinder and no annual service charge. Unvented cylinders require an annual charge of 60-100. If he says otherwise take no notce. That is 2,000 over 20 years for storing water.

No.
See above.

You can't have a pump on any mains pipe. Is the mains pressure and flow good? If so then go heat bank. They provide a wonderful buffer for the boiler and the CH circuit. You can have TRVs on all rads using a Grundfos Alpha pump too. No electric wall stat. Boiler cycling is elinminated.
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Poor advice. A programmable wall stat saves energy as well as making the house more comfortable.
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*I didn't fight my way to the top of the food chain to be a vegetarian.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

The idiot comes in again. Andrew is asking for advise, he doesn't need an senile amateur idiot to but in. Piss off loon. Go down the drop-in centre.
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To the OP - dribble doesn't understand even the most basic electrics (like most poor plumbers' mates) so avoids them at all costs.
Anyone with any real world experience will agree that a programmable thermostat saves energy as well as making the house more comfortable.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Fuck off idiot!
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So you are a foul mouthed plumbers mate who doesn't believe in saving energy? Of course you have a recent non-condensing boiler in your own hovel, so say no more.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Do reply to my posts. Fuck off idiot!
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I wouldn't be without ours. Great thing, particularly like being able to set different temperatures for different times of day.
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Skipweasel
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contains these words:

Individual room control is usually best. A centralised stat may switch out the heating when some parts of the house are calling for heat.
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We rarely shut any of our doors and it's a small house.
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contains these words:

You are living open plan, most do not live that way. Centralised temperature control is generally not a good thing. It can be used as a high limit that is about all, but only steps in when the individual temp control fails. In the case of different temperatures during the day it "might" make a difference, but then you can have a simple tamperproof low limit stat to make sure the building never gets below a certain temperature. I know few who use more than two temps on programmer stat.
Say you switch off the heating from a simple programmer as you are going out, and you never want the house to go below say 16C, then the low limit stat will ensure it never gets below that temp and maintains it around 16C. You come in switch the heating on and a fast warm up. Cheaper and simpler and easy to operate. Few people really understand programmable stats anyway. The point is, with individual room control you can have say the vacant back rooms set to around 16-18C by the TRV. You can't do that with a centralised programmer stat.
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It might be if one used something more sophisticated than TRVs. But that would be beyond the likes of you.

Then you've installed it incorrectly - if an average sized house.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Do reply to my posts. Fuck off idiot.
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Continual use of foul language now, eh, dibble? Is this the real you? BTW, still waiting for the police to arrive...
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*Parenthetical remarks (however relevant) are (usually) unnecessary *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:>> Do not reply to my posts. Fuck off idiot.

Do not reply to my posts. Fuck off idiot.
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