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What valves to replace radbots?

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by JamesPa 2 months ago
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 Powysperson
(@powysperson)
Eminent Member Member
Joined: 10 months ago
Posts: 11
Topic starter 01/11/2025 7:59 pm  

The installers put in Radbots which are famously rubbish, I've removed them all. What should I get to replace them please? I need something so I can tell visually that all the valves are fully open. Or at least one I can transfer from room to room to show this!

I'm going to attempt to balance the radiators myself as they are uneven in temp and mostly hot only at the top.

Thanks in advance!



   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3723
01/11/2025 8:51 pm  

Before answering the question definitively, its necessary to understand what the radbots are for?

Unless there is a very specific reason for them my suggestion is don't replace them, just sell them on eBay.  Alternatively refit them but leave then completely unscrewed for cosmetic reasons alone.  In either case the objective is that they have no effect and the valves will be fully open (their default position if there is no head on).  Then balance radiators on the LSVs for the desired temperature difference between rooms.

Alternatively you replace the radbots with decorators caps on the valves, and manually adjust them to balance, which is a bit easier than adjusting LSVs because they have a more linear response whereas LSVs tend to have an effect only in the last 0.5- (if you are very lucky) 2 turns.

All but one of my TRV heads are completely unscrewed, the house is run on a single zone, and I have adjusted the LSVs to get the desired temp difference between rooms (basically bedrooms cooler than living rooms).  The house has never been more comfortable and the heating cost (adjusted for the variation in energy costs with time) never lower.

 


This post was modified 2 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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 Powysperson
(@powysperson)
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Joined: 10 months ago
Posts: 11
Topic starter 02/11/2025 8:33 am  

Ah ok. So now that I have removed the Radbots, does that mean that the valve is fully open? ie on "5" or whatever? Because I can't tell from looking at them.

The radiators are still warm at the top and cold at the bottom so I'm guessing I have to balance the whole system via the LSVs?



   
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 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3723
02/11/2025 8:56 am  

Posted by: @powysperson
↑

Ah ok. So now that I have removed the Radbots, does that mean that the valve is fully open? ie on "5" or whatever? Because I can't tell from looking at them.

Yes.  Radbots just replace TRV heads.  TRV heads push the pin you can see on top of the valve down to shut the valve.  If there is no head the pin is fully up and the valve fully open ... unless the valve is stuck - which sometimes happens if you turn them down in summer.  You should be able to push the pin down about 1-2mm, if you cant it may be stuck down.  A sharp tap to the side with a hammer in line with the input to the radiator usually unsticks them.  The fact the rads are getting warm suggests that the pin isnt stuck however so I dont think this is a problem.

Posted by: @powysperson
↑

The radiators are still warm at the top and cold at the bottom so I'm guessing I have to balance the whole system via the LSVs?

Difficult to say.  Rads can be expected to be hotter near the inlet and colder near the outlet, and also hotter at top than bottom.  Remember that rads in low temperature heating systems (like ones powered by ASHPs) wont necessarily feel particularly warm, especially now when its pretty mild outside; thats the whole thing about low temp heating, nothing gets particularly hot.    If the rads are all fairly uniformly as you describe its not a balancing issue (which is about the differences between radiators not the temperature difference across any one radiator), in fact it may not be an issue at all just a result of cool rads and you threshold for something feeling warm.

Is the house getting warm?  Are you sure you actually have a problem?


This post was modified 2 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
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