Assembly and fitting of Thermostatic Radiator Valve

[Don]

I've been going through severe problems with my Heatline Compact S30 combi-boiler and recently had an engineer out to it under warranty. He noted that the TRV's the instaler had fitted were one-directional, said this would cause knocking and stress on the boiler and advised that they be changed to bi-directional. He also advised a room-stat which the installer also neglected.

I have drained the system and bought new Mistral bi-directional TRV's (with self seal tail). Here's where I am confused. The valve section allows the tail to move freely and does not appear to seal at all. All that is in the boxes are a two-way valve, two brass o-rings, two nuts and the sliding tail. I bought from PlumbBase, but I found the same item on ebay just now and it appears to have an extra brass part that did not come with the units I purchased. Am I missing parts from these or am I failing to realise how they work?

Also, the previous fitting had a female coupling on the bottom and the copper pipes seem to be attatched to what I presumed was the old copper o-rings! Unless I can get these off, the old fitting nut wont come off, and I cannot fit the new parts anyway. Any help would be gratefully appreciated. Thank you in advance.

[Dave Plowman (News)]

Nothing wrong with directional TVRs provided they are fitted correctly. Fit them the wrong way round and they may be noisy in operation.

If you have a room stat there mustn't be TVRs in that room.

[Don]

Thanks Dave. Unfortunately the directional TVR's were not fitted correctly and caused prolonged banging. The Bar-Gauge on the boiler itself would go crazy as the needle flipped. I will be installing a room stat asap. The new TVR's are a necessary measure right now to get Heatline to send an engineer again. Heatline say that they will not send out an engineer until the installation fault is made good. I've been unable to contact the original installer, and his Corgi number is now registered elsewhere in the country. If you copy/paste the following urls and replace hxxp with http you will see pictures of my problem at my photobucket account. I believe this is within the rules as I am not including any HTML in my post.

hxxp://i29.photobucket.com/albums/c283/neil_jung/NEWTRV.jpg hxxp://i29.photobucket.com/albums/c283/neil_jung/NEWTRVEXPLODEDVIEW.jpg hxxp://i29.photobucket.com/albums/c283/neil_jung/OLDTRV.jpg hxxp://i29.photobucket.com/albums/c283/neil_jung/StuckFittingOnPipe.jpg

[chris French]

In message , Don writes

It would have been easier to leave the http untouched. That isn't html and means most readers will spot it as a link and saved fiddling :-)

Anyway, what you have called brass 'O' rings are referred to as 'olives'. I've not used these but I assume that you use one nut and olive to attached the valve body to the tail. Best way is probably to fit the tail to the radiator slide on the nut and olive, then do up the nut. Once done up it will hold tight, presumably this is to allow for some adjustment.

Re the olive stuck on the pipe, this is pretty common. I have got away with leaving the olive on a pipe (with the nut) and then connecting it to a new fitting - but this does risk the joint leaking as the old olive may not seal correctly (an further addition to the bodge is top put a few wraps on PTFE tape around the olive first.

The are various ways to try and get it off, gripping it with apir of pliers or molegrips (mind the pipe it is easy to squash it) and twisting, using something like a junior hacksaw or a dremel to carefully mostly cut the olive - try not to nick the pipe, then use screwdriver etc. to pop it off. Put a adustable spanner underneath the nut at tap with a hammer to knock it off, etc.if there is enough slack in the pipe you can just cut the end of the pipe off (get a proper little pipe cutter for a neat cut) .

There have been threads on this try searching back on Google Groups.

When doing up the joints with olives, don't over do it. once you feel the joint start to 'tighten up - by hand preferably, just give an extra

1/8 - 1/4 quarter turn with the spanner . If it still leaks a bit later you can just give it a fuurther little tweak.

[Donwill]

To ensure identities are made clear and refering to my previous posts to this NG under the name of "Don", I am changing my name as follows. Cheers Donwill

[Dave Plowman (News)]

Right. If you refer to:-

chrome tube with the thread on it screws into the rad. Use PTFE tape on the threads - and you'll likely need a 'special' tool to tighten it. There's usually a hex on the inside for this purpose and the hex key can be bought from a PM, etc. Don't use grips on the outside as any damage here may prevent a seal. Now the nut shown next to the tube, then the brass olive, then the valve. When you tighten the nut to the TRV, the brass olive crimps onto the tube to make a seal. It's called a compression joint and is common in plumbing.

If the old unit was identical you could have re-used that part - but as you've found some are different fittings entirely. The type you have were common some years ago and IIRC sold by HomeBase.

What you need to do is saw a groove into the brass olive 'in line' with the pipe, ie across the side of the olive - but not all the way through, to avoid damage to the pipe. Then with a screwdriver twist the slot. The olive should then snap off. Just keep your fingers crossed that the pipe is long enough for the new style of TRV, as again this isn't standard between makes.

Clean the pipe with wire wool - again from a PM etc - until it gleams. Put the nut on first then the new olive. Make sure the pipe goes fully into the valve - there is a shoulder to set the right depth in the valve.

If it's too long it will need cutting to suit - use a proper pipe cutter again from a PM. If it's too short it will have to be extended. If the latter is the case, post again for advice on how.

[Christian McArdle]

Often you can use the old olive and nut on the new fitting.

If not, removing the old olive can be difficult. You can get special olive removers, or you can hacksaw a slot on the olive and try to ping it off with a flat blade screwdriver in the slot. However, if you nick the pipe itself with the hacksaw, it might never seal, so you must be careful.

Christian.

[Dave Plowman (News)]

If you look at the last pic, it's not an ordinary olive but one which fits across the top of the pipe. The 'nut' is actually a male bush so there's a female thread in the valve rather than the common male type.

I had these types (IIRC from Homebase) before changing to decent ones.

[Don]

Thanks everyone who took the time to share their knowledge. I managed to get the old olive off with the hacksaw groove/screwdriver twist technique. I sussed out how the compression joints worked and I almost had the first valve fitted! Unfortunately the tail is too long by about

5mill! I'm having trouble fitting the valves, even if everything was tightened the bottom pipe is too far from the valve to slot in. Is there a way to do this without removing the rads from the walls and bending the pipe somehow? Heres a pic showing the closest the connector can get to the pipe. There's less than 3 inches of copper pipe to work with from the join below (that feeds to the rad on the other side of the wall).

it be I should have been sold this model instead? It looks more like the ones I had fitted and took into PlumBase to show them.

can get hold of an angle-grinder to trim the tails but I'm brobably better served getting fully compatable fittings. Looking around there seem to be several models that might fit the bill. I was sold the Mistral M10, but I think it should have been the M11 (picture linked above). Unfortunately Plumbase where I purchased the M10's does not appear to stock them.

[Dave Plowman (News)]

You don't use angle grinders for this sort of thing. ;-) If you did need to cut down the supplied valve to rad pipe, use a hacksaw (carefully) then tidy the end with a file.

[<me9]

Just shorten the tail with a hacksaw or pipe cutter to the required length. it is just a short length of pipe. Don't forget to deburr it as well.

[Don]

Thanks again to everyone who replied. I've had a change of tack now anyway, and will only be replacing the bedroom TRV. I'm installing standard valves on the living area rads and fitting a room stat. From what I've been reading, and I've been reading every plumbing site I can find, it would be an all-round better option, saving energy and wear and tear on the boiler. By the time I hired a coring drill to go through the six-inch blockwork I reckon I'd be as well to pay for a cheapish wireless unit. Going to plumbase tomorrow morning so I'll hopefully get this finished over the weekend. My electric heater must be costing a fortune by now.