Hello all

I am looking forward to autumn/winter and want to fit TRV's to the upstairs
rads....upstairs always get hot whilst the living room downstairs if several
degrees cooler.  I know I have to drain the CH system to fit TRV's but will
the TRV be a direct replacement for the existing valves?   The fittings on
the TRV  look slightly different in size to the threads on the rads.  Do I
have to replace anything?

I have bough some B&Q TRV's, only cheap ones but I am not thinking about
getting a decent brand.  I hear that cheap ones can suffer from water hammer
and can often stick.

Any comments or advice would be greatly appreciated.

Thanks

On 2005-07-25 10:17:46 +0100, "vw-stuff"  said:


> I am looking forward to autumn/winter and want to fit TRV's to the upstairs
> rads....upstairs always get hot whilst the living room downstairs if several
> degrees cooler.  I know I have to drain the CH system to fit TRV's


Only enough to drain the upstairs rads if you're only doing those. I've 
heard that you can seal the feed and vent pipes to airlock the system 
to stop water escaping as an alternative.


> The fittings on the TRV  look slightly different in size to the threads 
> on the rads.
> 

Should all fit together nicely, you'll need a radiator allen key to 
unscrew the fittings from the radiators and some ptfe tape to seal the 
threads when you put the new ones in.

You may or may not need to adjust the length of the actual pipes.

I have bough some B&Q TRV's, only cheap ones but I am not thinking about

> getting a decent brand.  I hear that cheap ones can suffer from water hammer
> and can often stick.
> 

Check that you put the valves on the correct side of the rads.

-- 

Cheers

Derryck

> Only enough to drain the upstairs rads if you're only doing those. I've
> heard that you can seal the feed and vent pipes to airlock the system
> to stop water escaping as an alternative.


Where is the feed and vent pipes? Will they be in the loft with the CH water
tank?


> Should all fit together nicely, you'll need a radiator allen key to
> unscrew the fittings from the radiators and some ptfe tape to seal the
> threads when you put the new ones in.


Do I have to remove the threads from the rad?  Does the TRV thread screw
directly into the rad then replacing the old thread?


> Check that you put the valves on the correct side of the rads.


I have bought reversible TRV's, they have arrows pointing in both directions
on the 90 degree bend.  These can go on either end can't they?




"Derryck Croker" <derryck@cix.co.uk.invalid> wrote in message
news:2005072512123850073%derryck@cixcoukinvalid...

> On 2005-07-25 10:17:46 +0100, "vw-stuff"  said:
>
> > I am looking forward to autumn/winter and want to fit TRV's to the
upstairs
> > rads....upstairs always get hot whilst the living room downstairs if
several
> > degrees cooler.  I know I have to drain the CH system to fit TRV's
>
> Only enough to drain the upstairs rads if you're only doing those. I've
> heard that you can seal the feed and vent pipes to airlock the system
> to stop water escaping as an alternative.
>
> > The fittings on the TRV  look slightly different in size to the threads
> > on the rads.
> >
> Should all fit together nicely, you'll need a radiator allen key to
> unscrew the fittings from the radiators and some ptfe tape to seal the
> threads when you put the new ones in.
>
> You may or may not need to adjust the length of the actual pipes.
>
> I have bough some B&Q TRV's, only cheap ones but I am not thinking about
> > getting a decent brand.  I hear that cheap ones can suffer from water
hammer
> > and can often stick.
> >
> Check that you put the valves on the correct side of the rads.
>
> -- 
>
> Cheers
>
> Derryck
>

On 2005-07-25 12:42:41 +0100, "vw-stuff"  said:


>> Only enough to drain the upstairs rads if you're only doing those. I've
>> heard that you can seal the feed and vent pipes to airlock the system
>> to stop water escaping as an alternative.
> 
> Where is the feed and vent pipes? Will they be in the loft with the CH water
> tank?


Feed pipe from the CH cold water tank, vent from the hot out of the 
cylinder. I couldn't make this work when I tried it though, so would 
recommend partial draining.


> Do I have to remove the threads from the rad?  Does the TRV thread screw
> directly into the rad then replacing the old thread?


Undo the nuts on the valve and pull the valve off - it should look the 
same as the thermo one. I don't think you have to dismantle the rad any 
further so you probably don't need the allen key. But don't do the job 
on a Sunday afternoon just as the shops close...


> I have bought reversible TRV's, they have arrows pointing in both directions
> on the 90 degree bend.  These can go on either end can't they?


Sounds like it, but you may as well put it on the correct end anyway 
unless there's a good reason not to.

-- 

Cheers

Derryck

> Sounds like it, but you may as well put it on the correct end anyway
> unless there's a good reason not to.


Which is the correct end?


"Derryck Croker" <derryck@cix.co.uk.invalid> wrote in message
news:2005072618355243658%derryck@cixcoukinvalid...

> On 2005-07-25 12:42:41 +0100, "vw-stuff"  said:
>
> >> Only enough to drain the upstairs rads if you're only doing those. I've
> >> heard that you can seal the feed and vent pipes to airlock the system
> >> to stop water escaping as an alternative.
> >
> > Where is the feed and vent pipes? Will they be in the loft with the CH
water
> > tank?
>
> Feed pipe from the CH cold water tank, vent from the hot out of the
> cylinder. I couldn't make this work when I tried it though, so would
> recommend partial draining.
>
> > Do I have to remove the threads from the rad?  Does the TRV thread screw
> > directly into the rad then replacing the old thread?
>
> Undo the nuts on the valve and pull the valve off - it should look the
> same as the thermo one. I don't think you have to dismantle the rad any
> further so you probably don't need the allen key. But don't do the job
> on a Sunday afternoon just as the shops close...
>
> > I have bought reversible TRV's, they have arrows pointing in both
directions
> > on the 90 degree bend.  These can go on either end can't they?
>
> Sounds like it, but you may as well put it on the correct end anyway
> unless there's a good reason not to.
>
> -- 
>
> Cheers
>
> Derryck
>

vw-stuff wrote:

>> Sounds like it, but you may as well put it on the correct end anyway
>> unless there's a good reason not to.
>
> Which is the correct end?
>

The FLOW. But check the instructions with your TRV. Most seem to be 
'either-ended' nowadays - earlier makes were nearly all fitted to the flow 
(the end that gets hot first!:O)
Cheers
Gilbert

Have read that fitting the trv to the return can help reduce water hammer??
Anyone confirm/deny this.



"gilbert"  wrote in message
news:42e73fa4$0$92468$ed2619ec@ptn-nntp-reader03.plus.net...

> vw-stuff wrote:
> >> Sounds like it, but you may as well put it on the correct end anyway
> >> unless there's a good reason not to.
> >
> > Which is the correct end?
> >
> The FLOW. But check the instructions with your TRV. Most seem to be
> 'either-ended' nowadays - earlier makes were nearly all fitted to the flow
> (the end that gets hot first!:O)
> Cheers
> Gilbert
>
>

vw-stuff wrote:

> Have read that fitting the trv to the return can help reduce water
> hammer?? Anyone confirm/deny this.


I would imagine it was (or certainly used to be) more likely. Usually, a TRV 
has a spindle which is pushed by the actuator. If the spindle pushes against 
the flow it will steadily exert pressure until it closes. If the water flow 
is from 'behind' the spindle (i.e. out of the radiator) it can suddenly bang 
the valve shut against the seat as a result of the combined flow of water 
and direction of the valve seat. Bit like reseating a bath plug while the 
water is emptying.
Cheers
Gilbert


>
>
>
> "gilbert"  wrote in message
> news:42e73fa4$0$92468$ed2619ec@ptn-nntp-reader03.plus.net...
>> vw-stuff wrote:
>>>> Sounds like it, but you may as well put it on the correct end
>>>> anyway unless there's a good reason not to.
>>>
>>> Which is the correct end?
>>>
>> The FLOW. But check the instructions with your TRV. Most seem to be
>> 'either-ended' nowadays - earlier makes were nearly all fitted to
>> the flow (the end that gets hot first!:O)
>> Cheers
>> Gilbert