Hi,

I've read a few posts about the positive/negative points of combi
boilers.
I'm just selling my house which had an almost new combi boiler when I
moved in and to be honest I have been less than impressed by it. I
did speak to my neighbour who was a plumber and mentioned this to him,
he seemed to think that the Ariston that I had was not particually
good anyway.

I did not like that when only the hose pipe was on, its pressure was
useless. If I took a shower and either the washing machine or
dishwasher was on then the shower kept cutting out. Also quite often
it failed to start up.

Anyway the point of my post, we have found a house we like but it has
a combi boiler installed (in the loft ?), dont know what make it is
but my question is, is it more than likely to still have the same
problems as this is how combi boilers work ? Also its currently a 3
bed house with 8 rads, we will be extending to make a fouth bed room
and bigger kitchen so that will probably be 10 rads in total. Would
this be to much for a combi boiler ?

If so then what are my options of removing the combi boiler and
replacing it with a conventional system ? Could everthing be placed
in the loft still ?

Sorry for the long post, many thanks.

Marv.

On 1 Nov 2003 06:25:40 -0800, (Marv)
wrote:

Hi,

I've read a few posts about the positive/negative points of combi
boilers.
I'm just selling my house which had an almost new combi boiler when I
moved in and to be honest I have been less than impressed by it. I
did speak to my neighbour who was a plumber and mentioned this to him,
he seemed to think that the Ariston that I had was not particually
good anyway.

I did not like that when only the hose pipe was on, its pressure was
useless. If I took a shower and either the washing machine or
dishwasher was on then the shower kept cutting out. Also quite often
it failed to start up.

Anyway the point of my post, we have found a house we like but it has
a combi boiler installed (in the loft ?), dont know what make it is
but my question is, is it more than likely to still have the same
problems as this is how combi boilers work ? Also its currently a 3
bed house with 8 rads, we will be extending to make a fouth bed room
and bigger kitchen so that will probably be 10 rads in total. Would
this be to much for a combi boiler ?

If so then what are my options of removing the combi boiler and
replacing it with a conventional system ? Could everthing be placed
in the loft still ?



There are good,bad and indifferent combi boilers as with everything
else. If you really must have lashings of hot water ,on demand and at
mains pressure then consider fitting a pressurised hot water system
which is heated by a high efficiency conventional boiler.

joe

Sorry for the long post, many thanks.

Marv.

On 1 Nov 2003 06:25:40 -0800, (Marv)
wrote:



Anyway the point of my post, we have found a house we like but it has
a combi boiler installed (in the loft ?), dont know what make it is
but my question is, is it more than likely to still have the same
problems as this is how combi boilers work ? Also its currently a 3
bed house with 8 rads, we will be extending to make a fouth bed room
and bigger kitchen so that will probably be 10 rads in total. Would
this be to much for a combi boiler ?

It is typically not the heat output to radiators that is the problem,

There are three potential downfalls of a combi:

- Inadequate hot water production rate for the requirements of the
bath(s) and shower(s) in concurrent intended use. They are normally
specified with a rate in litres per minute for a temperature rise of
30 or 35 degrees. In cold weather when the water is at only a few
degrees above freezing, a shower (40 degrees) will be limited to
whatever the combi can do. Small ones with 9-11 lpm are going to be
disappointing.

Larger size combi boilers are available with outputs of 20 lpm or
more, although upgrade of the gas supply to the boiler may be required
if the pipe length is long or too small.

- Inadequate flow and pressure from the main, especially in an older
property. This can be measured at the kitchen tap. If you are
getting less than 20 lpm or so then results in general will be poor.
There are then two alternatives. a) Pay for the main to be upgraded,
which can be expensive. b) Install a conventional system with tank in
roof.

- Poorly implemented internal plumbing. This can be through re-use
of plumbing from an older roof tank/ gravity system providing
inappropriate distribution of water to the various taps and
appliances. It may be possible to correct this with flow
restrictors but often involves some replumbing or additional plumbing
so that feeds to certain locations are brought back to a common point.





If so then what are my options of removing the combi boiler and
replacing it with a conventional system ? Could everthing be placed
in the loft still ?

Yes it could. The appropriate solution would rather depend on the
limitations if any of the system.



Sorry for the long post, many thanks.

Marv.

..andy

To email, substitute .nospam with .gl

"Marv" wrote in message
om...
Hi,

I've read a few posts about the positive/negative
points of combi boilers.

There are few negative sides to a combi. the dissatisfaction arises when
they not sized or installed correctly. Fitted with a poor flowrate or with
an inadequate mains will not nor perform to expectations.

I'm just selling my house
which had an almost new combi boiler
when I moved in and to be honest I
have been less than impressed by it. I
did speak to my neighbour who was a
plumber and mentioned this to him,
he seemed to think that the Ariston that I
had was not particually
good anyway.

I did not like that when only the hose pipe
was on, its pressure was useless. If I took
a shower and either the washing machine or
dishwasher was on then the shower kept
cutting out. Also quite often
it failed to start up.

If your cold water mains can't cope, combi's are not the ideal solution as
they are mains fed. It appears your mains pressure/flow is poor. And that
goes for any mains fed system like Megaflows and thermal stores. Although
with poor mains pressure you can run a combi off a tank and pump in the loft
and save cylinder space in the tiny house below - sorted. This may be an
interim solution until your mains is updated.

They can go up to 22 litres/minute if you want. The average combi's are the
10 litre/minute cheapo's. For "most" households they the best solution in
simplicity and importantly, far less space taken up in tiny British homes.
Around 550,000 fitted per year says it all. For the majority of British
homes combi's are a panacea. They also heat the house up "real fast". They
are the ideal choice for DIYers when selecting a fully specced idiot proof
job like the Ariston Microgenus (far better than the earlier Ariston
models). BTW, A Microgenus 2 has just come out with 3 outputs of 24kW, 27kW
and a 13+ litres/minute 31or 32kW job .

Anyway the point of my post, we have
found a house we like but it has
a combi boiler installed (in the loft ?),
dont know what make it is
but my question is, is it more than likely
to still have the same problems as this
is how combi boilers work ?

Why not test it. Runs a few hot taps at once. It should have "decent" flow
with the kitchen and basin tap running at normal flow (not all full on).

Also its currently a 3
bed house with 8 rads, we will be
extending to make a fouth bed room
and bigger kitchen so that will probably be
10 rads in total. Would
this be to much for a combi boiler ?

A combi will cope with the heating side. They are over-powered for most
heating needs, as the instantly heating hot water takes a lot of power, so
they are sized for the hot water side.

If so then what are my options of removing
the combi boiler and replacing it with a
conventional system ? Could everthing be placed
in the loft still ?

A conventional systems in the loft is difficult, and probably not
achievable, and will entail a lot of upheaval. You would be better having a
new larger bore plastic water main from in from the street.

Depending on the cold mains pressure/flow. If this is fine and the combi is
not man enough for its intended hot water use. The best solution may be to
install another combi. Yes, another combi. Combi's are cheap. Have one do
downstairs heating, one upstairs, on two different time clocks. This means
upstairs can be off while downstairs is on, or vice versa. Then split the
hot water taps between the two combi's (have two showers on two different
combi's). A new gas supply will have to be run from the combi back to the
meter.



---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.524 / Virus Database: 321 - Release Date: 06/10/2003

"IMM" wrote in message ...
"Marv" wrote in message
om...
Hi,

I've read a few posts about the positive/negative
points of combi boilers.

There are few negative sides to a combi. the dissatisfaction arises when
they not sized or installed correctly. Fitted with a poor flowrate or with
an inadequate mains will not nor perform to expectations.

I'm just selling my house
which had an almost new combi boiler
when I moved in and to be honest I
have been less than impressed by it. I
did speak to my neighbour who was a
plumber and mentioned this to him,
he seemed to think that the Ariston that I
had was not particually
good anyway.

I did not like that when only the hose pipe
was on, its pressure was useless. If I took
a shower and either the washing machine or
dishwasher was on then the shower kept
cutting out. Also quite often
it failed to start up.

If your cold water mains can't cope, combi's are not the ideal solution as
they are mains fed. It appears your mains pressure/flow is poor. And that
goes for any mains fed system like Megaflows and thermal stores. Although
with poor mains pressure you can run a combi off a tank and pump in the loft
and save cylinder space in the tiny house below - sorted. This may be an
interim solution until your mains is updated.

They can go up to 22 litres/minute if you want. The average combi's are the
10 litre/minute cheapo's. For "most" households they the best solution in
simplicity and importantly, far less space taken up in tiny British homes.
Around 550,000 fitted per year says it all. For the majority of British
homes combi's are a panacea. They also heat the house up "real fast". They
are the ideal choice for DIYers when selecting a fully specced idiot proof
job like the Ariston Microgenus (far better than the earlier Ariston
models). BTW, A Microgenus 2 has just come out with 3 outputs of 24kW, 27kW
and a 13+ litres/minute 31or 32kW job .



Anyway the point of my post, we have
found a house we like but it has
a combi boiler installed (in the loft ?),
dont know what make it is
but my question is, is it more than likely
to still have the same problems as this
is how combi boilers work ?

Why not test it. Runs a few hot taps at once. It should have "decent" flow
with the kitchen and basin tap running at normal flow (not all full on).

Also its currently a 3
bed house with 8 rads, we will be
extending to make a fouth bed room
and bigger kitchen so that will probably be
10 rads in total. Would
this be to much for a combi boiler ?

A combi will cope with the heating side. They are over-powered for most
heating needs, as the instantly heating hot water takes a lot of power, so
they are sized for the hot water side.

If so then what are my options of removing
the combi boiler and replacing it with a
conventional system ? Could everthing be placed
in the loft still ?

A conventional systems in the loft is difficult, and probably not
achievable, and will entail a lot of upheaval. You would be better having a
new larger bore plastic water main from in from the street.

Depending on the cold mains pressure/flow. If this is fine and the combi is
not man enough for its intended hot water use. The best solution may be to
install another combi. Yes, another combi. Combi's are cheap. Have one do
downstairs heating, one upstairs, on two different time clocks. This means
upstairs can be off while downstairs is on, or vice versa. Then split the
hot water taps between the two combi's (have two showers on two different
combi's). A new gas supply will have to be run from the combi back to the
meter.



---


Hi,

Thanks for the feed back, that makes sense. Must be a poor cold water
mains that I have. The model I have here is a Microgenus. I have
since visited the new house and the water is 10 times more powerful
than I have, thats restored my confidence in Combi's. The idea of 2
combi boilers one for upstairs and one for downstairs is also very
interesting, especially when the washing machine/dishwasher is on.
Just a thought here and before you say I'm daft I work in computers
, I was wondering if it were possible to join the 2 systems together
on some sort of switch, for example if the 2 systems were joined but
shutoff from each other in the event of one breaking down would it be
possible to open the switch to make them one system ?

Anyway thanks again for your help and advice.

Marvin.

"Marv" wrote in message

A conventional systems in the loft is difficult, and probably not
achievable, and will entail a lot of upheaval. You would be better
having a
new larger bore plastic water main from in from the street.

Depending on the cold mains pressure/flow. If this is fine and the
combi is
not man enough for its intended hot water use. The best solution may be
to
install another combi. Yes, another combi. Combi's are cheap. Have
one do
downstairs heating, one upstairs, on two different time clocks. This
means
upstairs can be off while downstairs is on, or vice versa. Then split
the
hot water taps between the two combi's (have two showers on two
different
combi's). A new gas supply will have to be run from the combi back to
the
meter.

Thanks for the feed back, that makes sense.
Must be a poor cold water mains that I have.
The model I have here is a Microgenus.

This model operates on low water pressure, a reason why it may have been
chosen. It is also small and reliable.

I have
since visited the new house and the water is 10 times more powerful
than I have, thats restored my confidence in Combi's. The idea of 2
combi boilers one for upstairs and one for downstairs is also very
interesting, especially when the washing machine/dishwasher is on.
Just a thought here and before you say I'm daft I work in computers
, I was wondering if it were possible to join the 2 systems together
on some sort of switch, for example if the 2 systems were joined but
shutoff from each other in the event of one breaking down would it be
possible to open the switch to make them one system ?

Yes. But! "most" makers don't like you to combine the outputs, as they don't
want their technical depts answering queries all day from poor
installations. Technically there is no reason why you can't using
non-return valves.

One combi can serve a section of taps and the other another section to
spread the load independently and provide backup if one fails. But you may
need both combi's outputs to say provide a good flow to fill a bath and/or
shower.

Say you have two bathrooms and a shower in each. One combi does one
bathroom the other the other bathroom. Simple. After the washbasin and
before the bath and shower draw-offs of each bathroom join the pipes using a
few tees. "Before" the tee offs and after the basin draw-offs in each
bathroom, fit spring loaded non-return valves.

The way it operates is that the taps before the non-return valves operate
off separate combi's. Obvious. When any of the two baths or showers are
opened "both" combi's operate giving high flow.

If one combi fails then at least heating is available on another floor. One
bathroom will work off the remaining combi. This way is foolproof and
requires no user intervention.

For backup heating joining the two combi's heating circuits and using full
bore valves to open one and close the other is the way. But you need to
know what valves to open and close.

You could have both boilers on the heating circuit and split the circuit to
upstairs and down using zone two 2-port zone valves. A single pole double
throw wall switch (like a light switch)can have either boiler on run and the
other off. One drops out, press the switch and other operates. This gives
full backup, but the expensive of two extra zone valves.

In your case, adding a combi is not a great expense or upheaval. Just make
sure you do not exceed the meter loading. You are allowed 212 cu foot per
hour. divide the BTU/h of the combi by 1000 to get the cu ft/hour. A
80,000 BTU/h combi consumes 80 cu foot, so two is 160. Give enough for your
gas hob too.



---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.524 / Virus Database: 321 - Release Date: 07/10/2003