TRV Problem(s) !

[gg]

Hi, please could someone tell me if this is 'normal' !??

We have a CH system, 9 rads, 8 of which have TRV's...Ive noticed that setting to number FOUR allows the rooms to heat to around 21, (which the wife is happy with!)

However, once temp reached, the TRV's cut in and stop flow....and then dont generally allow water to flow back....until the temperature has dropped considerably (and sometimes only if you 'wiggle' the control now about a bit..)

Ive removed a couple of the sensor heads, and the pins all look fine and aren stuck at all

The sensors are Danfoss, and I believe are still available...they are all around 10 years old, could they just be too old and past their best?

Im not 100% sure how the TRV work to adjust the 'pushes' (is it wax??)

- but what would would be the normal temperature variation to enable them to 'reduce' when the temp drops to allow water to reflow??

Confused of Lincs!

PS, Ive lived with this for a couple of years....and just thought its time to try and fix!

[Staffbull]

Had the same problem with a few of mine, found they were full of dust, so just blasted them with an airduster can, and they were OK. Dunno if it will work for you though :-)

[EricP]

They do have a limited life.

From previous posts in here, the shed cheap stuff at £5 will last 5 years and the expensive branded stuff 15 years. So buy a cheap one and change it every 5 years.

Worth having a spare around anyway?

[gg]

Thanks, Ill give the 'air dust' a go...and see if helps

Does anyone know hopw they actually work?

Is it wax? Or some kind of liquid that expands??

Just interested....

Thanks

EricP wrote:

[John]

Does anyone know hopw they actually work?

Is it wax? Or some kind of liquid that expands??

Just interested....

Thanks

EricP wrote:

The technical term is Hysterisis. i.e. Off at 21 - On at 19.

I hate the damned things and haven't got any yet - prefer an electronic zone stat.

[The Natural Philosopher]

I thought it was a a wax filled capsule meself.

[gg]

Hmm..maybe my TRV's are now past their best then

They are Danfoss Thermostatic Rad Valves RAVL Series S 15mm

I think these are quite old, does anyone know if the 'heads/sensors' are still available to buy? Or are there any other part numbers that would fit to the existing 'pin' bit (excuse the lack of terminology)

Many thanks aga> John wrote: