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In my new property, there are TRVs aplenty. The first room we're decorating needs the radiator removing to strip paper and install reflective foil. The TRV has no identification on it and I can't find a cap to ensure it's fully off (the temperature's likely to drop to 10c overnight). Do you think I can trust the TRV turned down to minimum, or should I try to fit some kind of shim between the head and the valve?
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Is there a Zero on the control knob after the ice symbol?
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Turn the TRV down to zero then open the bleed valve gradually.
If fluid is still circulating it will come out the valve. If the TRV seals the supply there will be no leak. If it leaks, simply close the bleed valve.
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>>If the TRV seals the supply there will be no leak.
Perhaps until the temperature changes significantly in the night. And then it might. A lot.
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If you open the bleed screw without closing the TRV and lock-shield you'll still get water coming out of it.
If you don't know the history of the CH system I'd drain it completely anyway, flush and refill with fresh water and fernox.
Good opportunity to drag the rad outside and flush the carp out of it too.
BT. When you close the lock-shield make a note of how many turns it takes to close otherwise you might end up having to fiddle around getting the rad balance right again.
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>> BT. When you close the lock-shield make a note of how many turns it takes
>> to close otherwise you might end up having to fiddle around getting the rad balance
>> right again.
What on earth makes you think they were previously balanced.
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>What on earth makes you think they were previously balanced.
Good point.
If you can't use the sinks without flooding the place and the bathroom is dropping into a sinkhole, balanced rads might be a tad over-optimistic.
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>> Is there a Zero on the control knob after the ice symbol?
I'll have to have a look.
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I ask about the zero on the valve because some don't have it and you cant stop the flow of water completely.
I've also heard, but not tried it, that a Coke bottle screw top fits the valve outflow and can be used to seal the valve up.
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>> Is there a Zero on the control knob after the ice symbol?
Yes. So that should turn it off completely. I also found a 'decorators cap' in my shed, presumably from when I fitted TRVs here. Not that it would be suitable I suppose, as I suspect there isn't a standard for these things.
Now I need to figure out a way of draining the rad without staining the carpet with nice, black ferrous oxide.
I did consider fitting reflective foil behind it while it's off, but reading about it, it seems to be most effective on solid, outside walls, less effective on cavity walls and probably no use whatsoever on insulated, cavity walls.
After I sort this room, there's only another seven to do.
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Takes the thermo body off, then put a large jubilee clip round the valve body and plunger and tighten it.
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Sorted that radiator and the leak I introduced between the lock shield and the pipe! Why do they fit recessed drain taps that require a square key - had to find a plumber's merchant to sell me an appropriate key. I'm also now able to operate the (previously seized) isolator valve to the C/H top up tank.
Next question: One of the radiators is a double panel, convector (it's got square corrugations between the panels). I can't find a bleed screw on it. There's a couple of (heavily over-painted) domed heads. Do these reveal a bleed screw, or are they plugs into the water jacket?
The system consists of a wall-mounted boiler (Gloworm Ultimate), which I guess must be at least twenty years old. All the radiators have TRVs and in the airing cupboard, the tank has a TRV body. I'm sure I saw a capillary pipe running off this when I first viewed the property last April, but that's now gone. I presume there was some sort of remote activation to control the cylinder hot water temperature. I can't identify the type of body and it looks like the sort that requires an Allen screw to lock the head to the body. Anyone any idea what these things are called, so I may try and find a replacement head to control the hot water temperature? I appreciate it's not good practice to have all TRVs, in case they all close and the pump is pumping against closed valves. I've identified one radiator I can leave fully open.
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>One of the radiators is a double panel,..
On the, now replaced, double panel radiators I had the bleed screw was on top of one of the pipes connecting the two panels. It was set inside a small dimple to stop it protruding.
>..in the airing cupboard, the tank has a TRV body.
No 3-way valve, just a TRV controlled 2-way?
Is the pump in the airing cupboard and does the CH pipework branch off the pump there? If so, I'd be looking to see how much work is involved in changing to a 3-way with electric tank thermostat. Always better to have a system using bits a plumber keeps in his van or you can buy off-the-shelf from a DIY shed. Wiring, or lack of, might be your problem though.
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>> I had the bleed screw was on top of one of the pipes connecting the two panels. It was set >>inside a small dimple to stop it protruding.
No, these small dimples are on each panel.
>>Is the pump in the airing cupboard and does the CH pipework branch off the pump there?
Not found the pump yet, I guess it's contained within the boiler body. Definitely not in the airing cupboard, or the loft (as far as I can see). I can't see any 2 or 3-way valves. I'm hoping this old system will limp along for the colder months and I'll see about replacing it when it's warmer for a condenser boiler and put a small rad in the airing cupboard to replace the tank and keep SWMBO happy. But I'd like to find a way to stop the hot water being atboiler temperature.
Last edited by: bathtub tom on Thu 9 Dec 21 at 19:25
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>But I'd like to find a way to stop the hot water being atboiler temperature.
Normal 2-way "Zone" valve and electric thermostat? Is there somewhere you can get power (immersion htr maybe)?
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It would be nice to know what kind of system configuration this is. System boiler? combi boiler, what valves we have where? Control system?
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>> It would be nice to know what kind of system configuration this is. System boiler?
>> combi boiler, what valves we have where? Control system?
I'm not familiar with terms, but I presume it's what's called a system boiler. There's no valves or control system. The boiler's probably over twenty years old! The only control is what is effectively a time switch. All rads have TRVs and the hot water cylinder has a TRV body, but no head. As I said, I'm sure that when I first viewed the prperty in April there was a head on the water cylinder TRV with a capillary running off somewhere, presumably to some sort of wax cylinder that sensed the water cylinder temperature. I'd just like to know what this sort of TRV is called so I can google it and find a TRV head for this TRV body. I've had no luck so far.
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That's the sort of thing, unfortunately mine's only got the body and not the head, but it gives me a clue and now I can go do some research. Thanks.
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>> Next question: One of the radiators is a double panel, convector (it's got square corrugations
>> between the panels). I can't find a bleed screw on it.
>> There's a couple of (heavily over-painted) domed heads.
>> Do these reveal a bleed screw, or are they plugs into the water jacket?
>>
I have a similar radiator and have just checked it out
There is a small plastic domed cover on the corrugations side of each panel.
One is at the end of each panel i.e one on the left end and the other on the right.
Mine are not overpainted and a finger nail lifts the cover to expose the common square bleed screw.
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>>Mine are not overpainted and a finger nail lifts the cover to expose the common square bleed >>screw.
Thank you, I'll try that. I was reluctant to try and pry off the dome in case it plugged the water jacket.
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Just an observation - but I would get a proper plumber in to look at the system. Two reasons:
- you will then have a properly informed opinion of what needs to be done and the deficiencies of the current set up.
- you may find that as well as replacing the boiler etc, you may need to replace radiators and pipework. This would disrupti any decorating and/or new flooring you may now be doing
When I moved into my current house ~ 20 years ago the boiler was fairly new but the house was fitted with skirting radiators. Thses are both inefficient and (more importantly) were on a single circuit rather than feed and return. Replacing these meant pulling up floors for all new pipework!
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As he mentioned up-thread, his intention is to keep this limping along until the warmer months when he can look into a more modern/permanent solution.
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TRVs - Fullchat
