On Mon, 20 Sep 2004 22:44:33 GMT, "VisionSet"
wrote:


"VisionSet" wrote in message
...
I'm about to start the last major upheaval in my house.
Replaceing the ancient back-boiler.
...

I'll add a little more detail maybe you two can agree on something ;-)

House is 3-bed semi. 1 bathroom/toilet (ie one room). 6 rads + 1 teeny
one.

So the upshot is that nowadays combis are worth considering?
I'm think that when I had a look 6 years back that wasn't so much the case.

I am going to do all the work myself though get a corgi chap in for final
gas hook up to maintain boiler guarantee - that is the case is it not?

mains flow is 19.8 l/min - I guess that is okay.


Should be fine.


One issue that concerns me is reliability of a combi - my back boiler gets
next to no service and is 30 years old - glowworm model I'm finding it
excellent value! okay so it isn't quite the efficient boiler of today. Have
combis got more reliable of late?

I'd defer to Ed Sirett, John Stumbles or John Boilerdoc on that one
since they have regular contact, and raden because his company fixes
boards and supplies spares.

Like anything if you buy a decent one then results should be good.
Generally boilers of German origin or design seem to fare well.


If I put the boiler under the stairs (prefered location) available dims are
1240mm high x 770mm wide (width better alot less) depth slim as possible but
no actual restriction.

This would give you a fair choice. Most should fit that.



Hollow floors eases plumbing. All existing pipework is copper. 15mm
throughout except 22mm joins upstairs to downstairs rads. Shower is gravity
fed from same loft tank with very little head of water - perhaps 3ft max
shower head tank water level (full). Had a just tollerable dribble for too
long now :-( With a Trevie ceramic mixer valve.

There is the usual heating top up tank - Do any new real candidate systems
still need this?

Most boilers will run a pressurised primary.

You can DIY install a combi or a combi with indirect heatbank - i.e.
where the coil is in the primary circuit. This could be interesting
to do if you had a small combi relatively close to the kitchen and
used its directly produced water downstairs and then heated a cylinder
upstairs for the bathroom. In effect, you heat the cylinder by using
the CH part of the combi with the normal motorised valves as though
you were using a conventional boiler.

In a heatbank application you can buy the complete package, and
typically the heatbank cylinder is run vented. They can come with a
feed tank for this integral with the cylinder. You would heat the
heatbank via a coil and then the bulk (tertiary) water in the
heatbank is pumped through a plate heat exchanger to heat the DHW.
This arrangement can be DIYed because there is no large bulk of water
at mains pressure.

You could even have this arrangement with the CH vented and a direct
heatbank, but then the top of the heatbank must be above the highest
radiator. With a pressurised primary you do have more flexibility.


Can I put the whole shooting match in the loft?
Loft is too low for a full loft conversion so I might as well use it for
something - I think the one thing that I don't like about that my perception
of heat waste from the cylinder and boiler - I kind of liked the idea of
putting them somewhere I would benefit from any inefficiencies. However I
rather suspect these days those innefficiencies may well be negligble - or
at least unbenefittable from.

Yes you can. If you go for a decent condensing boiler, they run very
efficiently and you can also have the cylinder foamed to 100mm instead
of the typical 50mm.

You do have to board the relevant part of the loft and provide a rail.
THis is a Health and Safety requirement so that gas fitters can work
safely to service the boiler.




If it is ill advised to put the whole lot in the loft - which bits are a
good idea to put up there? House is 1930's with the hefty purlins and very
low since the rafter line is part in 1st floor. So height of any apparatus
is a factor.

No reason why not if it will fit. Positioning the cylinder where
the roof tank was should be OK, otherwise locate over a loadbearing
wall.






Andy - do you see away to ditch the tanks without going combi? Is that
pressurised system?

Yes you can do that.

One option are a heatbank as described. Albion do them as one
example. You can DIY this because the cylinder water is not
pressurised.

The other is a sealed pressurised cylinder.

This is not a DIY job as the Building Regulations require that a
trained fitter installs them. They are also supposed to have annual
maintenance under the terms of some insurance policies.



..andy

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