Hi,

I was thinking of upgrading our CH system in the next month
and like the idea of thermostatic rad valves.
I already have two Honeywell VT117E on 2 bedroom radiators.
I was going to buy another 6 and put them on some of the other
rads in the house.

Is it a good idea to have a lot of TRV's in a system and I
presume that the Honeywell ones are ok?

Thanks for any advice,
Matthew

On 4 Nov 2005 01:18:34 -0800, "Matthew" wrote:

Hi,

I was thinking of upgrading our CH system in the next month
and like the idea of thermostatic rad valves.
I already have two Honeywell VT117E on 2 bedroom radiators.
I was going to buy another 6 and put them on some of the other
rads in the house.

Is it a good idea to have a lot of TRV's in a system and I
presume that the Honeywell ones are ok?

It's a good idea to stick TRVs on all rads, except the bypass rad (If
there is one).

Honeywell will be OK

sponix

It's a good idea to stick TRVs on all rads, except the bypass rad (If
there is one).

How do you know if you need a bypass rad ?

Séan Connolly wrote:
It's a good idea to stick TRVs on all rads, except the bypass rad (If
there is one).

How do you know if you need a bypass rad ?

You *do* need a bypass for the case when all the other TRVs are closed
and the boiler/pump need to dump the hot water until they realise it's
time to turn off. It doesn't have to be a rad.

MBQ

You *do* need a bypass for the case when all the other TRVs are closed
and the boiler/pump need to dump the hot water until they realise it's
time to turn off. It doesn't have to be a rad.


Interesting. In my house at the moment all the rad's have TRV's, even the
bathroom towel one which would seem to be the obvious candidate for the
bypass rad. (Its a combi system btw)

Séan Connolly wrote:
You *do* need a bypass for the case when all the other TRVs are closed
and the boiler/pump need to dump the hot water until they realise it's
time to turn off. It doesn't have to be a rad.


Interesting. In my house at the moment all the rad's have TRV's, even the
bathroom towel one which would seem to be the obvious candidate for the
bypass rad. (Its a combi system btw)

When I say it doesn't have to be a rad, I believe some boilers
incorporate the bypass. Ours is a pipe in the airing cupboard with a
valve to restrict the flow like a lockshield.

MBQ

"sPoNiX" wrote in message
...
On 4 Nov 2005 01:18:34 -0800, "Matthew" wrote:

Hi,

I was thinking of upgrading our CH system in the next month
and like the idea of thermostatic rad valves.
I already have two Honeywell VT117E on 2 bedroom radiators.
I was going to buy another 6 and put them on some of the other
rads in the house.

Is it a good idea to have a lot of TRV's in a system and I
presume that the Honeywell ones are ok?

It's a good idea to stick TRVs on all rads, except the bypass rad (If
there is one).

Honeywell will be OK


I thought the rad nearest the room stat should not have a TRV?

wrote:

When I say it doesn't have to be a rad, I believe some boilers
incorporate the bypass. Ours is a pipe in the airing cupboard with a
valve to restrict the flow like a lockshield.


Or

http://www.screwfix.com/sfd/i/cat/95/p1725995_x.jpg


--

In an earlier contribution to this discussion,
PM wrote:


It's a good idea to stick TRVs on all rads, except the bypass rad (If
there is one).


I thought the rad nearest the room stat should not have a TRV?

Correct.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Matthew wrote:
Hi,

I was thinking of upgrading our CH system in the next month
and like the idea of thermostatic rad valves.

snip...

Is it a good idea to have a lot of TRV's in a system

yes & ought to save you CH fuel bills if used sensibly. OTOH if you
set all the TRVs to 27deg C you won't save on any bills, nor if you
leave all your internal doors open.

You'll do best to make all valves TRV except for the bypass rad (if you
have one - the bypass may be inside the boiler casing or in larger
setups a separate pipe loop near the boiler). You also need to be
cautious putting one in a room with a system controlling room
thermostat, otherwise they may joust with each other. Had trouble here
on one occasion with a rad which wouldn't turn on - the TRV was sitting
in the air stream from a computer fan :-))

and I
presume that the Honeywell ones are ok?


sorry can't help with specific brands, but when I installed the CH here
5 years ago there were 2 types on the market - reversible and
non-reversible. I checked on the manuactuer's help lines as to the
type before buying. The reversible ones could be put on either the
inlet or the outlet of the rad & are obviously more versatile. Non
reversible had to go on the inlet end only. I used the reversible type
& the only minor trouble has been a couple of times when the pin on
which the thermostat operates, has jammed. It just needs a mild clout
with a hammer to free it. It probably pays to vary the setting every
so often to avoid the pin settling into a fixed position.

Check for ease of removal of the thermostat head. No TRV turns off
completely at normal house temperatures when the CH is off. (ie your
house will normally be warmer than the 8deg C turn off of the TRV). So
if you want to remove a rad for decorating you have to take off the
head & screw on a cover to hold the pin completely down.

Most have a tab to set a tamper proof maximum ON. They vary as to how
easy they are to set (& alter).

Also watch for orientation - normally best operation is when the head
is horizontal away from the rad. Installing it vertically (upright)
parallel to the edge of the rad is giving the TRV a sensing problem.

HTH

wrote:

When I say it doesn't have to be a rad, I believe some boilers
incorporate the bypass. Ours is a pipe in the airing cupboard with a
valve to restrict the flow like a lockshield.

Even if you have some form of bypass, you still ought to have some form
of interlock to turn off the boiler once the house is up to the required
temperature. This is usually done with a room thermostat, and if you
have a room stat then the rad in that room should not be fitted with a TRV.

If don't have a room stat then you need some other form of interlock.
You could use a flow switch to detect when flow is effectively shut off
through all the TRVs (or when flow occurs through a spring loaded bypass
loop) to also shut off the boiler. This will not only save fuel, but
also prolong the life of the pump and boiler.

--
Cheers,

John.

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

In message . com,
writes

Matthew wrote:
Hi,

I was thinking of upgrading our CH system in the next month
and like the idea of thermostatic rad valves.

snip...

Is it a good idea to have a lot of TRV's in a system

yes & ought to save you CH fuel bills if used sensibly.

You also need to be
cautious putting one in a room with a system controlling room
thermostat, otherwise they may joust with each other.

Well, you just shouldn't do it really.

and I
presume that the Honeywell ones are ok?


sorry can't help with specific brands,

I imagine Honeywell are fine. I've always used Drayton, but any good
brand should be ok, I don't think cheapos are worth it.

Check for ease of removal of the thermostat head. No TRV turns off
completely at normal house temperatures when the CH is off. (ie your
house will normally be warmer than the 8deg C turn off of the TRV).

Er if your house is warmer than your TRV setting then surely the TRV
would be closed down?

but it's not wise to rely on this as it may open at an inopportune
moment, so yes it's best to use the cap if you ahve it.

Also watch for orientation - normally best operation is when the head
is horizontal away from the rad. Installing it vertically (upright)
parallel to the edge of the rad is giving the TRV a sensing problem.

Theoretically , but they all seemed to work fine in my old house when
vertically mounted.
--
Chris French

wrote in message
ups.com...


................Also watch for orientation - normally best operation is
when the head
is horizontal away from the rad. Installing it vertically (upright)
parallel to the edge of the rad is giving the TRV a sensing problem.

HTH


The instructions with my TRVs(made by Yorkshire) also recommend fitting to
the return(coldest) side of the radiators.

Keith G. Powell

In an earlier contribution to this discussion,
John Rumm wrote:


If don't have a room stat then you need some other form of interlock.
You could use a flow switch to detect when flow is effectively shut
off through all the TRVs (or when flow occurs through a spring loaded
bypass loop) to also shut off the boiler. This will not only save
fuel, but
also prolong the life of the pump and boiler.

The control system starts to get a bit complicated with flow switches. Once
the flow switch has detected low flow and switched everything off, there
will be *no* flow - so what turns it on again when the TRVs open? With the
alternative, of sensing by-pass flow, the system will hunt. Surely, a room
stat is by far the simplest way of achieving boiler interlock?!
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Set Square wrote:

The control system starts to get a bit complicated with flow switches. Once
the flow switch has detected low flow and switched everything off, there
will be *no* flow - so what turns it on again when the TRVs open? With the

You would nee some other mechanism. Could be a timer, or a pipe stat etc...

alternative, of sensing by-pass flow, the system will hunt. Surely, a room
stat is by far the simplest way of achieving boiler interlock?!

Yup agreed! and these days of wireless stats dead easy to install even
if not provided to start with.


--
Cheers,

John.

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

"John Rumm" wrote in message
...
Set Square wrote:

The control system starts to get a bit complicated with flow switches.
Once
the flow switch has detected low flow and switched everything off, there
will be *no* flow - so what turns it on again when the TRVs open? With
the

You would nee some other mechanism. Could be a timer, or a pipe stat
etc...

alternative, of sensing by-pass flow, the system will hunt. Surely, a
room
stat is by far the simplest way of achieving boiler interlock?!

Yup agreed! and these days of wireless stats dead easy to install even
if not provided to start with.


Any gotchas with wireless stats? What happends when the batteries die?
Good/bad makes etc.

Thanks
Pete

"PM" wrote:


"John Rumm" wrote in message
...
Set Square wrote:

The control system starts to get a bit complicated with flow switches.
Once
the flow switch has detected low flow and switched everything off, there
will be *no* flow - so what turns it on again when the TRVs open? With
the

You would nee some other mechanism. Could be a timer, or a pipe stat
etc...

alternative, of sensing by-pass flow, the system will hunt. Surely, a
room
stat is by far the simplest way of achieving boiler interlock?!

Yup agreed! and these days of wireless stats dead easy to install even
if not provided to start with.


Any gotchas with wireless stats? What happends when the batteries die?

On loss of comms or battery failure you can default the Honeywell CM6*
series to either totally off or 20% on / 80% off.




--

"Matt" wrote in message
...
"PM" wrote:


"John Rumm" wrote in message
...
Set Square wrote:

The control system starts to get a bit complicated with flow
switches.
Once
the flow switch has detected low flow and switched everything off,
there
will be *no* flow - so what turns it on again when the TRVs open?
With
the

You would nee some other mechanism. Could be a timer, or a pipe stat
etc...

alternative, of sensing by-pass flow, the system will hunt. Surely, a
room
stat is by far the simplest way of achieving boiler interlock?!

Yup agreed! and these days of wireless stats dead easy to install even
if not provided to start with.


Any gotchas with wireless stats? What happends when the batteries die?

On loss of comms or battery failure you can default the Honeywell CM6*
series to either totally off or 20% on / 80% off.

Is the stat and receiver a matched pair or will I be able to select a
channel and turn my neighbour's CH on and off? :-)

"PM" wrote:


"Matt" wrote in message
.. .

On loss of comms or battery failure you can default the Honeywell CM6*
series to either totally off or 20% on / 80% off.

Is the stat and receiver a matched pair or will I be able to select a
channel and turn my neighbour's CH on and off? :-)

Matched


--

chris French wrote:
In message . com,
writes

snip

Check for ease of removal of the thermostat head. No TRV turns off
completely at normal house temperatures when the CH is off. (ie your
house will normally be warmer than the 8deg C turn off of the TRV).

Er if your house is warmer than your TRV setting then surely the TRV
would be closed down?

sorry got a trifle muddled there. Problem (which I've experienced) is
that the minimum setting on a TRV is about 8deg. So if the room air
temperature is less than 8deg then the TRV opens regardless of whether
the CH is On or Off. This is when you need the cap if you wish to take
off the radiator for decorating. Also in practice TRVs do not make a
sharp cut off of flow at a specific operating point.

Hope that explains the point.

"Matt" wrote in message
...
"PM" wrote:


"Matt" wrote in message
.. .

On loss of comms or battery failure you can default the Honeywell CM6*
series to either totally off or 20% on / 80% off.

Is the stat and receiver a matched pair or will I be able to select a
channel and turn my neighbour's CH on and off? :-)

Matched


Many thanks Matt