I am planning to install CH in my house, however there is a huge
concrete floor between the only logical place for the boiler (will
probably be a Merlin Series 2000 oil boiler) and the hot water cylinder
/ radiators. Because about half the ground floor is concrete I am
planning to run all the heating pipes upstairs and drop down to
radiators.

The problem is that with the boiler a long way off downstairs (and the
pump too hopefully to prevent too much noise) how should I manage the
venting etc.

As far as I can tell I would need to have a vent pipe on the boiler
side of the pump for safety, but to ensure that air is extracted I
would also need either an automatic air vent (AAV) or a deaerator (such
as a Myson Aerjec).

My first stab at a plan can be found at www.mxf.org.uk/ch1.jpg

I am concerned about the vent pipe - I guess that being as long as it
is there is no chance of the pump sucking in air, but it's a very long
run that I am not sure if I need.

Any comments?

On 9 Aug 2005 10:08:22 -0700, "Matt Beard" wrote:

Any comments?
I can't imagine many people here recommending a gravity system, but
let's see. :-)

If there is nothing installed already, surely a big combi isn't much
more expensive and easier?

Mr F.

Matt Beard wrote:

I am concerned about the vent pipe - I guess that being as long as it
is there is no chance of the pump sucking in air, but it's a very long
run that I am not sure if I need.

Any comments?

If I read you symbol index correctly you have the vent shown in 15mm
pipe. 22mm is more normal for this to eliminate any possibility of it
getting blocked with scale etc.

Having said that, this would seem like an ideal candidate for being
installed as a sealed system if the boiler can support operation like this.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

If there is nothing installed already, surely a big combi
isn't much more expensive and easier?

With a mains pressure that struggles to reach 1 bar it's not a goer!

If I read you symbol index correctly you have the vent shown
in 15mm pipe. 22mm is more normal for this to eliminate
any possibility of it getting blocked with scale etc.

I was wondering - I just didn't want to run 8m or so of 22mm if I could
get away with 15mm!

I'd rather avoid going sealed - but maybe that's just me being
old-fashioned!

Opinions welcome...

In article .com,
Matt Beard wrote:
If there is nothing installed already, surely a big combi
isn't much more expensive and easier?

With a mains pressure that struggles to reach 1 bar it's not a goer!

Drivel seems to be rather lacking in advice here given he seems to think
everyone has 4.5 bar.

I'm in the same position as you here in this part of SW London. My mains
pressure is just over 1 bar, and the flow of cold I get to my kitchen
mixer via a 15mm main is near identical to the flow to the same mixer from
a hot water storage cylinder fed from a header tank.

So for adequate flow showers and bath filling, I've got to rely on large
bore pipes from a header tank and storage cylinder. A high rated combi
would be a waste of money.

--
*Make it idiot-proof and someone will make a better idiot.

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

"Dave Plowman (News)" wrote in message
...
In article .com,
Matt Beard wrote:

If there is nothing installed already, surely a big combi
isn't much more expensive and easier?

With a mains pressure that struggles to reach 1 bar it's not a goer!

Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread. Boy you are thick!

snip senile babble

In message ws.net,
Doctor Drivel writes

"Dave Plowman (News)" wrote in message
...
In article .com,
Matt Beard wrote:

If there is nothing installed already, surely a big combi
isn't much more expensive and easier?

With a mains pressure that struggles to reach 1 bar it's not a goer!

Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread. Boy you are thick!

My {deity of choice}, are you stupid


--
geoff

"raden" wrote in message
...
In message ws.net,
Doctor Drivel writes

"Dave Plowman (News)" wrote in message
...
In article .com,
Matt Beard wrote:

If there is nothing installed already, surely a big combi
isn't much more expensive and easier?

With a mains pressure that struggles to reach 1 bar it's not a goer!

Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread. Boy you are thick!

My {deity of choice}, are you stupid

Maxie, you will have to see through your hangover. I have not participated
in this thread. There is an excuse for Richard Cranium, as he just plain
thick. I expect better from you Maxie. Hang your head in shame.

Matt Beard wrote:

I'd rather avoid going sealed - but maybe that's just me being
old-fashioned!

Opinions welcome...

What is it youi have against sealed systems? Given your need to have the
main piping run at 1st floor level with drops to the radiators, a sealed
system would be better from the point of view of eliminating air locks etc.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

I guess that I still regard sealed systems as "newfangled" and best
avoided unless needs must. (OMG am I starting to get old already?)

More practically, there are three problems for me with this:

1) The slightly higher pressures makes leaks a little more likely (but
then if my soldering is up to spec...)

2) Space is very limited where the boiler is going (only just enough
room for the boiler).

3) There seems to be close to nothing useful available on how to design
a sealed systems, whereas there is quite a lot of info kicking around
for vented systems. (Although maybe not quite enough for my uses,
otherwise I wouldn't have to ask questions here!). It seems that the
general attitude seems to be "vented central heating? no problem, this
is how you do it... sealed system? nah, you need to get a professional
in for that"

Matt Beard wrote:

I guess that I still regard sealed systems as "newfangled" and best
avoided unless needs must. (OMG am I starting to get old already?)

;-) can't answer that!

More practically, there are three problems for me with this:

1) The slightly higher pressures makes leaks a little more likely (but
then if my soldering is up to spec...)

Well if your mains cold water does not leak, then you could say there is
no reason for your heating to either. There is a chance if you were
upgrading an existing system that you would need to replace some old
radiator valves if they weep after conversion. There is also the
possibility that any radiators that are on their last legs would give up
also - but in which case it is only a matter of time anyway.

Since you are talking about a new install (which no doubt will be
protected by inhibitor from the start and be using new components and
valves etc), it does not sound like it will be a problem. Look at the
bright side - if it does leak at least there is a limit to how much
water can come out!

2) Space is very limited where the boiler is going (only just enough
room for the boiler).

A sealed system need not take more space round the boiler. ("system"
boilers will include all the required components for a sealed system
inside their case anyway).

3) There seems to be close to nothing useful available on how to design
a sealed systems, whereas there is quite a lot of info kicking around
for vented systems. (Although maybe not quite enough for my uses,
otherwise I wouldn't have to ask questions here!). It seems that the
general attitude seems to be "vented central heating? no problem, this
is how you do it... sealed system? nah, you need to get a professional
in for that"

One of the traps you may be falling into is that most sealed system
installs they are actually far simpler than conventional vented ones.
Hence there is less information available since there is less you need
to know.

Have you read Ed's FAQ?

http://www.makewrite.demon.co.uk/SealedCH.html

Many folks will start with a system boiler. This includes the pump,
expansion vessel, overheat protection, and possibly even the filling
loop. To turn this into a complete heating system you just add pipes,
radiators, and a room thermostat.

If you want stored water heated as well, then you would need a cylinder,
a stat (and/or flow switches if you want to get clever!), and suitable
valve arrangements just as you would on a vented system.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Maybe I'll go for a Worcester Danesmoor system boiler then... there
isn't much choice for an oil-fired system boiler lwss than 400mm wide!

Bumps the price up a bit, but I guess it's worth it if I don't have to
do all the venting.

I guess I will still need some sort of AAV at the top of the system
though.

On Wed, 10 Aug 2005 08:22:26 -0700, Matt Beard wrote:

Maybe I'll go for a Worcester Danesmoor system boiler then... there
isn't much choice for an oil-fired system boiler lwss than 400mm wide!

Bumps the price up a bit, but I guess it's worth it if I don't have to
do all the venting.

I guess I will still need some sort of AAV at the top of the system
though.

The boiler will almost certianly contain one it would be a good idea to
add one at the top. In any case a bleed point of some description will be
essential at the high points.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

On 10 Aug 2005 06:23:14 -0700, "Matt Beard" wrote:

I guess that I still regard sealed systems as "newfangled" and best
avoided unless needs must. (OMG am I starting to get old already?)

More practically, there are three problems for me with this:

1) The slightly higher pressures makes leaks a little more likely (but
then if my soldering is up to spec...)

I did this conversion a couple of years ago to a system that was 15
years old then but had been well looked after. The only thing that I
did in terms of renewal was to change the lockshield valves which had
been original and not of particularly good quality with some Pegler
Terrier ones. Apart from that - no issue.

You do need to calculate the total water volume of the system from
radiator data sheets and amount in pipes. There is a table of
numbers for the required size of a pressure vessel to go with the
water volume and initial pressure of the vessel.

Note that it is not a problem if you oversize the vessel.



2) Space is very limited where the boiler is going (only just enough
room for the boiler).

Some boilers have an internal vessel which may be large enough for the
system - typically they are. In my case, the capacity was not quite
enough so I added a second vessel externally.

One option is to install the vessel in the loft in the space formerly
or otherwise occupied by the feed/expansion tank. It needs to be
insulated of course, and you need a bleed vent on the pipe near it to
let out the air.



3) There seems to be close to nothing useful available on how to design
a sealed systems, whereas there is quite a lot of info kicking around
for vented systems. (Although maybe not quite enough for my uses,
otherwise I wouldn't have to ask questions here!).

If you want a comprehensive heating design book that includes this and
a lot of other useful stuff, I can recommend the Domestic Heating
Design Guide published by the HVCA (www.hvca.org.uk) at £19.50


It seems that the
general attitude seems to be "vented central heating? no problem, this
is how you do it... sealed system? nah, you need to get a professional
in for that"


Sealed heating is not an issue if you can plumb competently.
Pressurised HW storage systems have a bunch of regulation around them.


--

..andy

To email, substitute .nospam with .gl

In article ws.net,
Doctor Drivel wrote:
Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread.

That's the one true statement you've made in years.

--
*My dog can lick anyone

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

In article ws.net,
Doctor Drivel wrote:
With a mains pressure that struggles to reach 1 bar it's not a
goer!

Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread. Boy you are thick!

My {deity of choice}, are you stupid

Maxie

[snip usual drooling}

And again, in a second post.

--
*Two many clicks spoil the browse *

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

"Dave Plowman (News)" wrote in message
...
In article ws.net,
Doctor Drivel wrote:
With a mains pressure that struggles to reach 1 bar it's not a
goer!

Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread. Boy you are thick!

My {deity of choice}, are you stupid

Maxie

The attendants have let him at the machine.

"Dave Plowman (News)" wrote in message
...
In article ws.net,
Doctor Drivel wrote:
Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread.

That's the one true statement you've made in years.

Boy you are sharp.

In article ws.net,
Doctor Drivel wrote:
Drivel seems to be rather lacking in advice here

Dr Drivel hasn't given any advise on this thread.

That's the one true statement you've made in years.

Boy you are sharp.

That's the second one.

--
*Why don't sheep shrink when it rains?

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