Uvented cyl v Thermal store.

[IMM]

I was a doing Google and I caught this. My News server din't pick it up. It requires attention.

Geosolar Heating ( [e-mail])

At the risk of being associated with 'dumb > plumbers' I'll give my reasons for recommending > an unvented cylinder rather than a thermal > store. I've got nothing against the technology > of a thermal store but personally feel its had > its day now that condensing boilers will soon > be mandatory to the mass market.

Confusing passage but let's see....

I agree that an unvented cylinder must > be installed by a trained person. IMM > says that UV cyls can explode and while > true it is rare due to the safety features that > are mandatory. UK regulations are lot > stricter than many countries were UV cyls > have been the norm for many > years.

The point is that they can explode, and do. If one explodes an insurance company will not pay out if the unvented cylinder was not serviced.

To the points in question; > 1. Reinstating the air bubble in a megaflow > is not a difficult task.

It is for a pensioner. Many local authorities have removed unvented cylinders as they had too much hassle of drips from vent pipes because the air bubbles were never re-instated by the residents, or the pressure vessels failed. They had an army of men attending these problems.

2. 1" copper overflows are not required > unless the route to discharge is extraordinarly > long. The tundish has a 22mm output and this is > sufficient for most installations. However, the > discharge pipework must not be plastic.

The large metal pipe extracts heat from a house 24/7. For this reason eco houses don't us them. DPS do a heat banmk that doesn't require an overflow, so no penetration of the external building fabric.

3. KISS. Which is easier to understand; > the UV cyl or a heatbank?

Both. If dumb plumbers can't understand a thermal store or heat bank they should work on the milk.

4. Solar. As far as I know OSO and Viessmann > are the only UV cyls to have dual coil models. > Yes, the solar won't heat your radiators, but > since solar systems are designed to work at > their peak in summer, surely this a moot point?

It is not. Solar panels work in winter with clear strong sun. A solar coil in an integrated thermal store supplying DHW & CH will have solar generated heat used for CH and DHW. A solar coil in an unvented cylinder is only available for DHW.

5. condensing boilers. I commented this > elsewhere in the NG. UV cyls are a better > option with a condensing boiler.

Clearly untrue. A heat bank with DHW and heating sections, with the heating section controller from an outside weather compensator will perform very efficiently with condensing boiler

With inefficient boilers there is no such choice > between an uv cyl and heatbank.

????

6. DIY. Yes I'll agree that a heatbank > can be DIY-ed. This suggests > the owner has some interest in the > heatbank technology, which is fair > enough.

Or wants high flow DHW cheaply as he can do it himself. It is not a matter if he has fad for thermal store technology. A DIYer can't fit an unvented cylinder.

Future owners may not be so inclined.

Future owners will not know the difference. All they know is that a heat bank will give them high pressure DHW. Also a heat bank can go up to 10 bar, whereas I know of no unvented cylinder that is above 3.5 bar (they are pressure (reduced).

Still, future employment > for 'plumbers' when the next owners > rip it out to put a megaflow in?

Ignorance from dumb plumbers. I know of one housing estate that were fitting with Flowmaxes about 12 years ago . Some of the Flowmaxes developed simple faults, such as flow blending valves failing and the likes. The naive owners contacted the local dumb lumbers and said it is best to rip them out and fit a tank in the loft. There are a number of tank now in lofts, when a £30 part would have solved the problem.

I can give you examples of dumb plumbers putting in a rad system when a perfectly adequate forced air system is there. All was required was the unit repairing.

Most plumber are only good for drains and gutters and replacing bathroom suites.

7. The marque. A 'Megaflow' has become > something of a must-have. > Probably due to marketing and keeping > up with the Jones.

Marketing has promoted an inferior technology that is clear. Also develoers fitting them besuse they easy is also promoted them. Heat banks are just as easy. Obviuosl a cheap was done somwhere. "Megaflows a must have" Please get real.

Still, the educated customer wins out. > It may be a plus-point on a future house sale.

A megalflow or thermal store? When a customer sees high pressure mains hot water he is impressed whether Megaflow or heat bank. Heat bank give higher pressures, up to 10 bar.

8. Boiler cycling. Any system is susceptable > to this if badly installed. I've not seen a modern > UV cylinder which causes the boiler > to cycle before it reaches the desired temperature.

I have.

I only install the keston celsius 25, which has > some features to avoid cycling.

So you blinded by a boiler with load compensating control; the "only" type you fit.

9. All in one packages. Not something I go > for myself but just a personal choice.

And no reason given. Not impressed.

There are equally valid pros/cons > for this type of unit.

You should be more objective when assessing these matters. You have everything to gain.

Something tells me you want unvented cylinders to be the norm as only BBA people can fit them. They are NOT cheap and BBA fitting not cheap either. Your mind is poisoned by vested interest.