Towel rails on DHW recirculation?

[Dan F]

Hi,

 

Looking at best way to heat first floor bathroom towel rails. Main options are electric and water obvisouly:

 

Electric is easiest but least efficient.  Water would typically require dedicated first floor plumbing for this, if you have no first foor heating otherwise (we won't).  This additional plumbing means  i) extra plumbing/cost ii) additional heat losses which may be underiable in the summer ii) ASHP potentially only coming on to heat towel rails.

 

So, I was wondering if the water recirculation (which we'll likely have come on based on motion) can be used to heat towel rails?  I assume you'd need copper or brass, rather than standard steel to avoid corrosion affecting the water you shower in, but is this doable? Has anyone done it? Or am I being too creative?

 

Thanks,

[Russell griffiths]

a lad I knew a few years ago did this on a couple of houses he built, no idea if it worked but he liked the idea. 

[nod]

1 hour ago, Russell griffiths said:

a lad I knew a few years ago did this on a couple of houses he built, no idea if it worked but he liked the idea. 

We purchased three of these for the bathrooms Stainless Steel 20 year guarantee In reality they are an expensive decoration As like rest of the first floor heating it’s never used due to high levels of insulation 

At the previous hours we where always changing towel rails due to rusting 

[JFDIY]

Stainless steel rail would work, or as you say brass or copper.

 

I'd also consider electric, if you had it on a programmable thermostat it could be only on when you needed it for a few hours at a time, switched off by room temperature or timed.

 

I fitted one of these Elements (link) I grossly oversized it for the towel rail as it is thermostatically controlled, so cuts off once your set point is achieved. Mine is on a timer and remembers the temperature set point even if power is disrupted.

 

Think we're looking at 20p per day for 5hrs time when on, though mine is on central heating as well so it will be lower.

 

 

[joe90]

Yes I went with electric towel rads on timers, cost pennies to run .

[PeterW]

Depends on your DHW heating system ..? ASHP..?? Gas..? Oil..?

 

This method would mean you have the towel rail on permanently including in the summer. That is a big heat load into the house if it is well insulated. 
 

It would also mean you are constantly topping up the hot water tank, and that would be in peak electric time, and potentially an inefficient use of the heat source as it may be short cycling. 

[Dan F]

29 minutes ago, PeterW said:

Depends on your DHW heating system ..? ASHP..?? Gas..? Oil..?

ASHP + UVC.

 

29 minutes ago, PeterW said:

This method would mean you have the towel rail on permanently including in the summer. That is a big heat load into the house if it is well insulated. 

That's a good point, I was assuming you'd use a thermostatic valve like on a radiator, but exactly how this would work on  I don't know.

 

31 minutes ago, PeterW said:

It would also mean you are constantly topping up the hot water tank, and that would be in peak electric time, and potentially an inefficient use of the heat source as it may be short cycling. 

You woulnd't be constantly topping up the water if it's on the DHW recirculation loop, as that water comes back round to the tank.  You will potentialy need to heat UVC to account for losses in DHW recirculation and towel rails but this is an existing loop that already exists (where UVC acts as buffer), rather than something new just for towel rails. 

 

Also, doesn't make sense to hook up with UFH because when I'm cooling slab in summer I don't want to also cool towels!

 

 

[Jeremy Harris]

Probably worth comparing the increased capital cost against any saving in running cost through life.  Electrically heated towel rails on timers are very cheap to run.  We have two, but only use one most of the time.  It uses on average about 40 W when it's turned on (allowing for the thermostat cycling it on and off).  We have it set to be on for an hour in the morning and an hour in the evening, which seems fine, as it stays warm for around an hour after being turned off, and the towels always seem to dry quickly.

 

The morning timed period is during the E7 off peak period, the evening one is during the peak rate period, so the running cost is slightly under 1p per day.  Allowing for three weeks a year when we are away from home, the total annual cost is around £3.25.  With a bit of luck, I may live for another 20 years, so if the capital cost, plus running cost, difference for a DHW heated towel rail system was no more than about £65 it might be worth doing.  If it was any more than this it probably wouldn't.

[Dan F]

@Jeremy Harris Think you're right given those numbers; electric is simplest and while not efficient use/cost will be very low.  Using DHW would mean more expensive brass/copper/stainless towel rails and would also couldn't go directly on DHW circulation anyway, else it would be always on.

 

Any recommendations for good electric towel rail brand that can be integrated with automation e.g. loxone?

[joth]

On 24/04/2020 at 00:40, Dan Feist said:

So, I was wondering if the water recirculation (which we'll likely have come on based on motion) can be used to heat towel rails?  I assume you'd need copper or brass, rather than standard steel to avoid corrosion affecting the water you shower in, but is this doable? Has anyone done it? Or am I being too creative?

 

 

I wondered about this, but when I looked through the WRAS and Building regs requirements it had requirements that if you do this, the DHW secondary return must operate at 60+ deg C or so, and must run "continuously" (or wording around that effect). I could not tell if N hours a day would satisfy this "continuous" requirement, and of course would add another requirement to have the secondary return operate all year even if away on holidays (ah, those were the days when being out the house for a week at a time didn't seem ludicrous).

Combined with the excellent points @Jeremy Harris makes on here of the simplicity of direct electrical heating (for towel rads and bathroom UFH) we decided to go that way.

 

On 25/04/2020 at 17:56, Dan Feist said:

Any recommendations for good electric towel rail brand that can be integrated with automation e.g. loxone?

 

To the second part of the question, I'm curious what could stop any heating element work with loxone? Hook them on a 16A relay extension and away you go? I guess a very high end  element could  have  built in smarts that need a manual prodding if the power is removed? So just go for a good value, dumb element.

 

Edited April 27, 2020 by joth

[Bitpipe]

We also don't have any heating upstairs but have a separate wet circuit for the towel rads in each bathroom with a separate channel on the controller.

 

In the grand scheme, this should not be expensive and you will want independent control of that circuit as you will not want it on in summer but will want DHW circulating for washing.

 

We also have electric wire ufh in the tiled bathrooms but this was an afterthought just after first fix.

 

TBH the towel rads are only on over winter - rest of year they're just towel hangers and due to MVHR, towel dry very quickly.