I've just been chatting to a loft conversion company about loft
conversions and they seem to be of the opinion that I shouldn't try
and extend my open pumped CH system to the loft - but as far as I can
see all I need to do is raise the header tank to be above the loft
rads (all be it not by much) and it should just work.

Has anyone done this - does it work efficiently?

The builder seems to favour scrapping my perfectly functional boiler
and going for a new combi sealed system - which seems to me rather
over the top.

Thanks,

Ben

In an earlier contribution to this discussion,
Ben Freeman wrote:

I've just been chatting to a loft conversion company about loft
conversions and they seem to be of the opinion that I shouldn't try
and extend my open pumped CH system to the loft - but as far as I can
see all I need to do is raise the header tank to be above the loft
rads (all be it not by much) and it should just work.

Has anyone done this - does it work efficiently?

The builder seems to favour scrapping my perfectly functional boiler
and going for a new combi sealed system - which seems to me rather
over the top.

Thanks,

Ben


You may have difficulty getting the header tank high enough to prevent the
system from pumping over - unless you've got lots of headroom above the new
living accommodation.

If your existing boiler is suitable, you could convert to a
sealed/pressurised system without having to change the boiler. Check your
boiler installation manual. [If you haven't got one, you may be able to
download one from the manufacturer's website].
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

I've just been chatting to a loft conversion company about loft
conversions and they seem to be of the opinion that I shouldn't try
and extend my open pumped CH system to the loft

Is your old boiler not capable of sealed operation? What make and model is
it?

Do you plan to have a shower/bath up there?

Christian.

In article ,
Set Square wrote:
You may have difficulty getting the header tank high enough to prevent
the system from pumping over - unless you've got lots of headroom above
the new living accommodation.

Unless you've got a flat roof, I'd say there'd be plenty room for a CH
header tank. The domestic water tank is usually the problem.

The head on my system is probably less than 6 feet from top of rad to
water level in tank, but works fine on over three stories.

--
*Great groups from little icons grow *

Dave Plowman London SW 12
RIP Acorn

On 9 Mar 2004 05:45:32 -0800, (Ben Freeman)
wrote:

I've just been chatting to a loft conversion company about loft
conversions and they seem to be of the opinion that I shouldn't try
and extend my open pumped CH system to the loft - but as far as I can
see all I need to do is raise the header tank to be above the loft
rads (all be it not by much) and it should just work.

Has anyone done this - does it work efficiently?

The builder seems to favour scrapping my perfectly functional boiler
and going for a new combi sealed system - which seems to me rather
over the top.

Thanks,

Ben

There are a couple of options here.

1) You can certainly do what you've described as long as the pipework
is organised properly from the header tank to the rest of the system
to avoid pumping over of water or sucking down of air. This means
that the feed pipe and the vent pipe must reach a point directly
connected to the boiler (no motorised valves in the way) no further
than about 150mm apart. Alternatively you can use a special venting
device such as a Myson Aerjec

www.bes.ltd.uk part 11334

The other piece to this is that you need a minimum head from the tank
to the top of the highest radiator. Most boiler manufacturers say
0.5 to 1m - you need to check.

In a former house with an attic bedroom and loft next to it, I was
able to site the tank up quite high and used a long 300mm high
radiator to get the head to an adequate level.

2) If the boiler permits it, you could convert the whole system to
sealed operation. Look for Ed Sirett's FAQ on doing this.
It would be a very easy job and removes the issue completely.

I suspect that the builder is talking up the value of the deal.......





..andy

To email, substitute .nospam with .gl

Is your old boiler not capable of sealed operation? What make and model is
it?

Potterton Netahet 10/16 (approx 15 yrs old but still in excellent
nick)
The manual states that I need an optional "over heat thermostat kit"
which I very much doubt I will be able to get hold of.

Do you plan to have a shower/bath up there?

yes - but I had planned on fitting a small pump / flow sensor if the
water pressure is low.

Ben

My loft room is only 2m high at the highest point. The header tank is in
there as high as it can go and the new rad in there works fine. Kept my
existing (12year old) boiler and the whole CH system works well still. My
builder was against putting in a combi system as he reckoned I would
probably get leaks elsewhere due to the increased pressure and (not
unreasonably) he wasn't prepared to be responsible for fixing existing
pipework. I certainly didn't see any point in replacing everything to avoid
that.

Chris O
_____________________________________________---
"Ben Freeman" wrote in message
om...
I've just been chatting to a loft conversion company about loft
conversions and they seem to be of the opinion that I shouldn't try
and extend my open pumped CH system to the loft - but as far as I can
see all I need to do is raise the header tank to be above the loft
rads (all be it not by much) and it should just work.

Has anyone done this - does it work efficiently?

The builder seems to favour scrapping my perfectly functional boiler
and going for a new combi sealed system - which seems to me rather
over the top.

Thanks,

Ben

"Chris O" wrote in message ...
My loft room is only 2m high at the highest point. The header tank is in
there as high as it can go and the new rad in there works fine. Kept my
existing (12year old) boiler and the whole CH system works well still. My
builder was against putting in a combi system as he reckoned I would
probably get leaks elsewhere due to the increased pressure and (not
unreasonably) he wasn't prepared to be responsible for fixing existing
pipework. I certainly didn't see any point in replacing everything to avoid
that.

I think I'll go for keeping my current system with a raised header
tank and only convert to sealed if it proves problematic.

Cheers for all the advice.

Ben

My builder was against putting in a combi system as he reckoned I
would probably get leaks elsewhere due to the increased pressure
and (not unreasonably) he wasn't prepared to be responsible for
fixing existing pipework.

It's still worth doing. If increasing the pressure by one bar causes leaks,
then your system will collapse in six months anyway. If I wasn't reasonably
confident myself, I'd rather that this happened with a central heating
installer on the premises.

Christian.

yes - but I had planned on fitting a small pump / flow sensor if the
water pressure is low.

Yes, you wouldn't be able to have a shower easily. The shower head would be
above the water tank. This would cause you to need a negative head pump
(which is basically a kick start attachment), but you may still get airlock
problems. You really should consider replacing your hot water cylinder with
a heat bank or unvented cylinder, which will provide mains pressure hot
water (and run off your existing central heating system).

As for the radiators, there is another alternative to pressurising or moving
the header tank that may require less work. Basically, the new loft circuit
is done as a pressurised system with its own expansion tank, pressure
relief, filling loop, pump etc. It is then tied into the existing system
with a plate heat exchanger, which appears like a radiator to the existing
system and as a heating boiler to the loft system. If you get the controls
right, you can even have separate timing on the new circuit so you don't
have to heat it during the daytime. Andy Hall fitted a system with a similar
principle (but for different reasons, of course) for his shed.

Christian.

"Ben Freeman" wrote in message
om...
"Chris O" wrote in message
...

My loft room is only 2m high at the highest point. The header tank is in
there as high as it can go and the new rad in there works fine. Kept my
existing (12year old) boiler and the whole CH system works well still.
My
builder was against putting in a combi system as he reckoned I would
probably get leaks elsewhere due to the increased pressure and (not
unreasonably) he wasn't prepared to be responsible for fixing existing
pipework. I certainly didn't see any point in replacing everything to
avoid
that.

I think I'll go for keeping my current system with a raised header
tank and only convert to sealed if it proves problematic.

Cheers for all the advice.

Ben,

Firstly a Neatheat is an old very inefficient boiler with some parts now not
available. While at it, it is best to get rid of this and install a modern
high efficient boiler. If you install a condensing boiler your gas bills
will drop approx 30-40% from what you currently pay, and even more when the
extension is fitted. Also while you are at it, install thermostatic rad
valves on al the rads and replace the lockshield valves on the other end of
the rads. In short revamp your system. It will obviously cost you more,
but worth it in the end, as you will have to go through this process sooner
or later, and most probably sooner with an old Neataheat. Best get it all
out of the way and pipes hidden with the extension, etc.

A Neataheat cannot have a sealed system.

How many bathrooms have you got, and how many will there be when the
extension is complete?

"Christian McArdle" wrote in message
. net...
yes - but I had planned on fitting a small pump / flow sensor if the
water pressure is low.

Yes, you wouldn't be able to have a shower easily. The shower head would
be
above the water tank. This would cause you to need a negative head pump
(which is basically a kick start attachment), but you may still get
airlock
problems. You really should consider replacing your hot water cylinder
with
a heat bank or unvented cylinder, which will provide mains pressure hot
water (and run off your existing central heating system).

As for the radiators, there is another alternative to pressurising or
moving
the header tank that may require less work. Basically, the new loft
circuit
is done as a pressurised system with its own expansion tank, pressure
relief, filling loop, pump etc. It is then tied into the existing system
with a plate heat exchanger, which appears like a radiator to the existing
system and as a heating boiler to the loft system. If you get the controls
right, you can even have separate timing on the new circuit so you don't
have to heat it during the daytime. Andy Hall fitted a system with a
similar
principle (but for different reasons, of course) for his shed.

Best get rid of the old inefficient near clapped out boiler for a new
condenser boiler, replace all radiator valves and any rads which look dodgy.
Depending on hot water requirements a mains pressure Pandora heat bank is
probably the best way to go.

In article ,
IMM wrote:
If you install a condensing boiler your gas bills
will drop approx 30-40% from what you currently pay,

Please ignore this rubbish. As usual, he's plucking figures from the air.
20% saving is more likely simply by changing a Neataheat to a decent
condenser.

--
*If horrific means to make horrible, does terrific mean to make terrible?

Dave Plowman London SW 12
RIP Acorn