I currently have a system with pumped heating, gravity HW. Heating has TRV
on all rads except bathroom (bypass). There are no room therms or cylinder
therms.

I intend to add a tank therm and zone valve to give the ability to heat CH
only and avoid overheating the tank.

Should the 2 port valve be fitted near the tank or the boiler - and should
it be on the flow or return?

Is there such a thing as a RF tank thermostat to prevent the need for a long
wiring run?

thanks

On Mon, 07 Jun 2004 18:27:00 GMT, "James" wrote:

I currently have a system with pumped heating, gravity HW. Heating has TRV
on all rads except bathroom (bypass). There are no room therms or cylinder
therms.

I intend to add a tank therm and zone valve to give the ability to heat CH
only and avoid overheating the tank.

Should the 2 port valve be fitted near the tank or the boiler - and should
it be on the flow or return?

It doesn't matter that much - whichever is the easier. You need to
make sure that the boiler will accept not having the gravity circuit
and will need to arrange that the boiler switched live is turned off
when neither the HW cylinder or the CH demand heat. THis depends on
the wiring and control scheme, but look at Honeywell's site for the
different wiring plans, S, Y and W. You may also need a bypass for
the boiler.


Is there such a thing as a RF tank thermostat to prevent the need for a long
wiring run?

Yes. Danfoss Randall make one that matches their room thermostat
range.


thanks


..andy

To email, substitute .nospam with .gl

Should the 2 port valve be fitted near the tank or the boiler - and
should
it be on the flow or return?

It doesn't matter that much - whichever is the easier.

The problem is getting the wiring from the downstair utility loft - to the
main house loft. Using a RF tank therm would be easier to fit the valve
downstairs near the boiler if thats ok.

You need to make sure that the boiler will accept not having the gravity
circuit
and will need to arrange that the boiler switched live is turned off
when neither the HW cylinder or the CH demand heat. THis depends on
the wiring and control scheme, but look at Honeywell's site for the
different wiring plans, S, Y and W.

The boiler (potterton netaheat) has a switch inside for gravity or pumped -
even with the valve the system will still be gravity.

The manual show the curent layout (gravity hw) and shows an "optional valve"
so the boiler should accept it ok.

Will have a look on the honeywell site for the diagrams.


You may also need a bypass for the boiler.

Currently the bathroom rad is always on - acting as a bypass. To sort this
out if I add a TRV to this, and then plumb in a hydralic bypass across the
flow and return pipes to the boiler have I done the right thing?




Is there such a thing as a RF tank thermostat to prevent the need for a
long
wiring run?

Yes. Danfoss Randall make one that matches their room thermostat
range.

Will check it out. Thanks

Thanks for the help

"Andy Hall" wrote in message
...
On Mon, 07 Jun 2004 18:27:00 GMT, "James" wrote:

I currently have a system with pumped heating, gravity HW. Heating has
TRV
on all rads except bathroom (bypass). There are no room therms or
cylinder
therms.

I intend to add a tank therm and zone valve to give the ability to heat
CH
only and avoid overheating the tank.

Should the 2 port valve be fitted near the tank or the boiler - and
should
it be on the flow or return?

It doesn't matter that much - whichever is the easier. You need to
make sure that the boiler will accept not having the gravity circuit
and will need to arrange that the boiler switched live is turned off
when neither the HW cylinder or the CH demand heat.

On the few C plans I have done (if this is a C plan), I can remember that
you need to be careful that the valve does not cut off the overflow to the
header tank and so is usually on the return side of the hot water tank.

Adam

On Mon, 07 Jun 2004 20:22:40 GMT, "Gaz" wrote:

Should the 2 port valve be fitted near the tank or the boiler - and
should
it be on the flow or return?

It doesn't matter that much - whichever is the easier.

Sorry I misread the detail of your post. Are you planning to only
fit a zone valve and thermostat and not convert to fully pumped?

If so, this is a C-plan arrangement, and as Adam says, you must be
careful not to position the zone valve such that it would interrupt
the path to the vent.



The problem is getting the wiring from the downstair utility loft - to the
main house loft. Using a RF tank therm would be easier to fit the valve
downstairs near the boiler if thats ok.

Notwithstanding siting to avoid blocking the vent path, it shouldn't
matter.


You need to make sure that the boiler will accept not having the gravity
circuit
and will need to arrange that the boiler switched live is turned off
when neither the HW cylinder or the CH demand heat. THis depends on
the wiring and control scheme, but look at Honeywell's site for the
different wiring plans, S, Y and W.

The boiler (potterton netaheat) has a switch inside for gravity or pumped -
even with the valve the system will still be gravity.

The manual show the curent layout (gravity hw) and shows an "optional valve"
so the boiler should accept it ok.

Yes it should so scrub the comment about Y,S and W plan and look at C
which is much easier anyway.



Will have a look on the honeywell site for the diagrams.


You may also need a bypass for the boiler.

Currently the bathroom rad is always on - acting as a bypass. To sort this
out if I add a TRV to this, and then plumb in a hydralic bypass across the
flow and return pipes to the boiler have I done the right thing?

It depends on what the boiler manufacturer's manual says on that -
i.e. whether a bypass is needed if you convert to C plan.





Is there such a thing as a RF tank thermostat to prevent the need for a
long
wiring run?

Yes. Danfoss Randall make one that matches their room thermostat
range.

Will check it out. Thanks

Thanks for the help


..andy

To email, substitute .nospam with .gl

Should the 2 port valve be fitted near the tank or the boiler - and
should
it be on the flow or return?

It doesn't matter that much - whichever is the easier.

Sorry I misread the detail of your post. Are you planning to only
fit a zone valve and thermostat and not convert to fully pumped?

The intention was just to add a 2 zone valve and NOT convert to fully pumped
on the basis that water heat up is not a problem - and fitting is
simplified.

If so, this is a C-plan arrangement, and as Adam says, you must be
careful not to position the zone valve such that it would interrupt
the path to the vent.

Right - So need to fit value on pipe that does not have vent fitted!!!
Should be ok.

The intention was just to add a 2 zone valve and NOT convert to fully
pumped
on the basis that water heat up is not a problem - and fitting is
simplified.

Beware that the valve and any pipework changes could affect the natural
convection, requiring you to add a pump anyway.

Right - So need to fit value on pipe that does not have vent fitted!!!
Should be ok.

Also, it shouldn't block the supply of fresh water to the boiler. Safety
requires the vent to be clear to allow steam to escape and the supply to be
clear to allow water to quench the boiler. Although this only applies if
there is no automatic overheat cutout, this is very likely to be the case on
an old gravity circulated boiler).

Christian.