Performance of TRVs
 

Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

Leaving my digital probe thermometer in one position in a room is giving me
a swing of a few degrees in temperature, and I would like to chase down the
reason for this differential.
---
Dave Fawthrop dave hyphenologist co uk
20,000 free e-books at Project Gutenberg! http://www.gutenberg.org
For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/
also PG Nos 2888, 3232, 17472, 17799

Performance of TRVs
 

"Dave Fawthrop" wrote in message
...
Has anybody got any figures on the performance of Thermostatic Room
Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

Leaving my digital probe thermometer in one position in a room is giving
me
a swing of a few degrees in temperature, and I would like to chase down
the
reason for this differential.

Because themostats generally do not open and close at the same temperature.
Even when hysteresis defeating mechanisms are employed it is rare and
proabably confined to
purely solid state devices. Certainly a TRV is never going to perform in
this way.

--
Mike W

Performance of TRVs
 

On Sun, 04 Feb 2007 21:17:20 +0000, Dave Fawthrop
wrote:

Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

Leaving my digital probe thermometer in one position in a room is giving me
a swing of a few degrees in temperature, and I would like to chase down the
reason for this differential.
---
It varies too much from make to make and unit to unit.

Identical TRVs here have slightly different characteristics.

Performance of TRVs
 

In article ,
Dave Fawthrop writes:
Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

On a small sheet of paper in the box they came in.

Leaving my digital probe thermometer in one position in a room is giving me
a swing of a few degrees in temperature, and I would like to chase down the
reason for this differential.

Try measuring the temperature right next to the TRV head.
The TRV can't do better than keeping that constant.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Performance of TRVs
 

In an earlier contribution to this discussion,
Andrew Gabriel wrote:


Try measuring the temperature right next to the TRV head.
The TRV can't do better than keeping that constant.

It can't even do that under all conditions. A given knob setting and room
temperature will result in a particular flow restriction. But the *required*
flow restriction to maintain a constant room temperature will vary,
depending on the heat losses (heavily influenced by outside temperature) and
on pump pressure - which will depend on what all the other TRVs in the
system are doing. At best, TRVs can only provide crude temperature control.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Performance of TRVs
 

On Feb 4, 9:17 pm, Dave Fawthrop
wrote:
Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

Danfoss RAS-C leaflet says;

frost * 8
I 12
II 16
III 20
IIII 24
I C

I don't think there is a standard.

You won't get precise control throughout the room because, even if the
TRV were operating perfectly, it would take some time for a change in
output to be measureable at all points in the room. It's cheap &
cheerful but good enough for most purposes. To get exact control of
room temperature, you'd need to circulate something like 10 AC/hr
through a convector heater.

Even then, people's perception of comfort involves both humidity &
radiant heat, as well as air temperature. E.G., the kids complain
they're cold in the morning despite room air temperature being 21,
'cos floors and walls are cold. Kids are warm in the evening at the
same air temperature 'cos floors & walls have heated up & so less heat
lost through radiation.

Performance of TRVs
 

On Sun, 04 Feb 2007 21:17:20 +0000, Dave Fawthrop wrote:

Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C
open to closed = ??? degrees C
There must be a specification somewhere.

Leaving my digital probe thermometer in one position in a room is giving me
a swing of a few degrees in temperature, and I would like to chase down the
reason for this differential.
---

They are not made well enough and combined with other factors there is too
much variation between units. Hence the relative scale using numbers,
final user tweaking is needed to get the settings right.



--
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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards