HELP! I'm trying to decide between boilers again but it's finally crunch
time and I need to buy this week.

Looking at www.discountedheating.co.uk I'm puzzled by the fact that
system boilers are cheaper than the equivalent non-system boiler; this
doesn't seem logical because there's an extra pump, expansion vessel and
safety valve in the system boiler. Does it just reflect sales volumes or
is there something more subtle?

There seems to be nothing between the W-Bosch 28HE and Glow worm 30SXI;
prices and features are all similar BUT both have fixed-speed pumps
rather than self adapting pumps (e.g. alpha) - is this likely to be a
problem with a 3 zone (+ DHW) system?
The alternative is a non-system boiler 29HE or 30HXI but that's another
£140+ for the boiler, alpha pump, expansion vessel, etc.

Any suggestions on how to choose (other than availability) between W-B,
GW or ... ???
--
Dave S
(The return email address is a dummy)

System boilers are used in conjunction with pressurised hot water tanks such
as megaflow,this may be why they are cheaper,and because they are so
expensive this reflects in the cost.

Alex wrote:
System boilers are used in conjunction with pressurised hot water tanks such
as megaflow

Are you sure? I have a Glow-worm 30SXI in a conventional sealed system
with indirect HW cylinder. It seems to work perfectly well.

The system is too new for me to comment on the boiler's reliability, but
otherwise I am very happy with it.

--
Tony

"Tony Eva" wrote in message ...
Alex wrote:
System boilers are used in conjunction with pressurised hot water tanks
such
as megaflow

Are you sure? I have a Glow-worm 30SXI in a conventional sealed system
with indirect HW cylinder. It seems to work perfectly well.

The system is too new for me to comment on the boiler's reliability, but
otherwise I am very happy with it.

A system boiler has:
- an integral pressure vessel
- integral pump.

Heating boilers:
are basic boilers with no pump or pressure vessel, that usually can be
pressurised, by a kit or external pressure controls and pump or can be open
vented. Most buy them to be open vented.

A combi is a system boiler with and added water section.



_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 120,000 groups
Unlimited download
http://www.usenetzone.com to open account

A System Boiler (SXI) for use with sealed systems where there is a need to
retain the traditional hot water storage and central heating systems.

The above is quoted from the glow worm website there words not mine

In article ,
Doctor Evil wrote:
A system boiler has:
- an integral pressure vessel
- integral pump.

Heating boilers: are basic boilers with no pump or pressure vessel, that
usually can be pressurised, by a kit or external pressure controls and
pump or can be open vented. Most buy them to be open vented.

A combi is a system boiler with and added water section.

So all combis have an integral pressure vessel and integral pump?

--
*Toilet stolen from police station. Cops have nothing to go on.

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 7 Feb 2005 00:43:23 +0000 (UTC), "Alex"
wrote:

A System Boiler (SXI) for use with sealed systems where there is a need to
retain the traditional hot water storage and central heating systems.

The above is quoted from the glow worm website there words not mine

This doesn't mean that system boilers are only meant to be used in
systems with pressurised hot water storage.

As mentioned before, a system boiler is just a regular sealed system
boiler with the inclusion of a pressure vessel, pump, and a pressure
release value already plumbed and wired within the casing of the
boiler.

This is mainly just to make installation into a new sealed system, or
an existing open system thats being converted to a sealed system,
simpler, quicker and cheaper.

The main disadvantage is that you cant then choose the size of pump
and pressure vessel to suit a non typical system, and the case of the
boiler is typically a fair bit bigger.

Alex wrote:
System boilers are used in conjunction with pressurised hot water tanks such
as megaflow,this may be why they are cheaper,and because they are so
expensive this reflects in the cost.


Sorry Alex but that's not correct. System boilers are normally for
pressurised heating systems, the type of DHW cylinder is irrelevant
providing it's indirect.

--
Dave S
(The return email address is a dummy)

"Dave" wrote in message
...
HELP! I'm trying to decide between boilers again but it's finally crunch
time and I need to buy this week.

Looking at www.discountedheating.co.uk I'm puzzled by the fact that
system boilers are cheaper than the equivalent non-system boiler; this
doesn't seem logical because there's an extra pump, expansion vessel and
safety valve in the system boiler. Does it just reflect sales volumes or
is there something more subtle?

Reflects sales volumes. 99% of combi's are systems boilers with a water
section added. 60-70% of all boilers sold (1 million a year) are combi's,
so competition is hard and prices are driven down. It is sometimes cheaper
to buy a combi and not use the water section than buy an equivalent power
system boiler. I a few contractors who do this.



There seems to be nothing between the W-Bosch 28HE and Glow worm 30SXI;
prices and features are all similar BUT both have fixed-speed pumps
rather than self adapting pumps (e.g. alpha) - is this likely to be a
problem with a 3 zone (+ DHW) system?
The alternative is a non-system boiler 29HE or 30HXI but that's another
£140+ for the boiler, alpha pump, expansion vessel, etc.

Any suggestions on how to choose (other than availability) between W-B,
GW or ... ???
--
Dave S
(The return email address is a dummy)


_________________________________________
Usenet Zone Free Binaries Usenet Server
More than 120,000 groups
Unlimited download
http://www.usenetzone.com to open account

There seems to be nothing between the W-Bosch 28HE and Glow worm 30SXI;
prices and features are all similar BUT both have fixed-speed pumps
rather than self adapting pumps (e.g. alpha) - is this likely to be a
problem with a 3 zone (+ DHW) system?

No. I have a 3 zone + DHW system running from the Greenstar 28HE and it runs
just fine. Zones are upstairs/downstairs/kitchen/DHW. I intend to add a
couple more zones. I do have an automatic bypass as well, though, which
should reduce noise when running a low load.

Christian.

A System Boiler (SXI) for use with sealed systems where there is a need
to
retain the traditional hot water storage and central heating systems.

The above is quoted from the glow worm website there words not mine

I'm afraid you have misunderstood. This quote simply states that it uses a
sealed primary system. It says nothing about the design of the hot water
cylinder beyond implying that it must be an indirect cylinder. It will work
with gravity fed, pumped gravity, mains pressure (i.e. Megaflo) or heat
banks.

Christian.