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How to choose Towel Rails for an ASHP

Air Source Heat Pumps (ASHPs)

Last Post by Mars 1 hour ago

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Renewables345

(@renewables345)

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Topic starter 16/09/2025 10:28 am

Hi all,

I'm struggling a bit here. I am currently quoting up my first ASHP job. I have done the heat loss which comes out at 10.6kW. There is a bathroom which has a heat loss of 570 watts and a WC with a 400 watt heat loss. The bathroom currently has a 1m wide by 0.5m high towel rad, and can only go up to 0.6 high. In the WC it is 1m high and 0.6m wide. These don't match the outputs necessary but I can't find any which will even get close to fit in the space. What would you do in this scenario and is there anywhere you would recommend buying your towel rads from?

Thanks

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Mars

(@editor)

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16/09/2025 12:01 pm

@rob-nezard is this one you can assist with in terms of sizing or guidance?

@renewables345, UK Radiators is a safe and reliable place to purchase rads from because of their transparent approach to emitters.

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JamesPa

(@jamespa)

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16/09/2025 12:03 pm

Posted by: @renewables345

↑

Hi all,

I'm struggling a bit here. I am currently quoting up my first ASHP job. I have done the heat loss which comes out at 10.6kW. There is a bathroom which has a heat loss of 570 watts and a WC with a 400 watt heat loss. The bathroom currently has a 1m wide by 0.5m high towel rad, and can only go up to 0.6 high. In the WC it is 1m high and 0.6m wide. These don't match the outputs necessary but I can't find any which will even get close to fit in the space. What would you do in this scenario and is there anywhere you would recommend buying your towel rads from?

Thanks

So far as I have been able to establish towel rails are essentially useless for low temperature heating, they simply dont emit sufficient energy.

In my bathroom I left the existing towel rail and relied on overspill from the adjacent hall, which works for me. When I run a bath or have a shower steam heats the room anyway! Other installers have suggested a normal radiator, a fan radiator or an electric insert to the towel rail for the short time its actually in use. You can get add-on (sometimes magnetic) rails for normal rads so thats another option.

For my money this is an area where flexibility and customer preference takes over!

This post was modified 2 hours ago 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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Mars

(@editor)

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16/09/2025 12:19 pm

Posted by: @jamespa

↑

So far as I have been able to establish towel rails are essentially useless for low temperature heating, they simply dont emit sufficient energy.

You've beaten me to the punch. I had this very conversation with Brendon yesterday relating to our towel rails and he said exactly that. They don't emit significant heat and they can affect the rest of your rad/emitter circuit. I will be covering this in our video of the retrospective work we're having done, but Brendon has highlighted to me that towel rails need to be throttled down almost fully.

This post was modified 1 hour ago by Mars

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Rob Nezard

(@rob-nezard)

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16/09/2025 12:23 pm

@editor Hi Mars, sure I will do my best. The only way to increase heat output with any kind of emmitter (which is what is required when moving to lower temperatures) is to increase the surface area of the emitter.

If increasing height/width is not an option then your best bet would be to try and find something with more tubes.

We have one model that is particularly popular for lower temperature systems as there are 2 sets of tubes.

UKRADIATORS.COM "https://ukradiators.com/products/crossmoor-white-towel-radiator-h1000mm-x-w500mm?variant=46742482256190"

White Towel Radiator - H1000mm x W500mm - Crossmoor | UK Radiators

Order this Crossmoor White Towel Radiator H1000mm x W500mm today from UK Radiators with free delivery.

- this may work for the second room mentioned however the first does sound like it is going to be a struggle.

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JamesPa

(@jamespa)

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16/09/2025 12:26 pm

Posted by: @editor

↑

Brendon has highlighted to me that towel rails need to be throttled down almost fully.

Why? To stop them acting as a bypass?

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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Mars

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16/09/2025 12:29 pm

@jamespa yes, to essentially prevent them consuming unnecessary flow and to allow "more" for the remainder of the heating circuit.

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