Spar bath and underfloor heating

[johnad]

I'm looking to install underfloor heating in my bathroom ( approx 7x8 )
I will be replacing my bath at the same time and fitting a spar bath
There is an existing point that was for a old electric shower mounted in a airing cupboard as this is an existing curcuit could this be split up to run both the bath pump and the underfloor heating ?
I assume that as this is in a bathroom it will involve part P ?
Advice needed please .

 

[PrenticeBoyofDerry]

All domestic electrical installs, involve part P!

What do you have with regards to RCD protection?

 

[OwainDIYer]

I'm looking to install underfloor heating in my bathroom ( approx 7x8 )

metres or feet?

(well, some people do live in big houses ...)

What is the cable size and fuse rating of the shower circuit and what are the loadings of the floor heating and the spa?

 

[deadshort]

Hi, yes you shower supply could be used if you retain the switch in the airing cupboard and use it to supply two switched fused spurs fused down to the appropriate rating.

All wiring in your bathroom must be RCD protected.

Kind regards,

DS

 

[DetlefSchmitz]

I have always taken the view that underfloor heating in a small bathroom is a waste of effort. A decent towel rail will probably supply more useful heat, in more ways than one.

I use wet heating in my house, I guess the same may apply to electrical heating. But if you don't believe it do the calculations. How much bare floor area is left to heat the room?

 

[johnad]

Hi yes the CU is a new duel RCD type and the cable is 6mm on a 32a mcb
I haven't looked into the loadings yet but the bath will just be a pump so shouldn't be to high and I have seen some underfloor heating mats on a 13a flu so looking at the size I would need hopefully 13a would be ok but I will have a Google and check.
I was just wondering that if a have an existing supply I could connect everything myself ?

And the 7 x 8 was feet not meters lol (I wish)

I may try and talk the wife out of the heated floor and just fit a rad I have just read that it takes about an hour to reach temperature (wish me luck)
But I will still need to connect the bath

 

[ban-all-sheds]

I will be replacing my bath at the same time and fitting a spar bath

Do you mean one which you bought at a local convenience store?

I assume that as this is in a bathroom it will involve part P ?

Being a bathroom is irrelevant. As PBoD says, Part P (in fact all of the Building Regulations) applies to any work whatsoever on fixed electrical cables or fixed electrical equipment located on the consumer’s side of the electricity supply meter which operate at low or extra-low voltage and are—
(a) in or attached to a dwelling;
(b) in the common parts of a building serving one or more dwellings, but excluding power supplies to lifts;
(c) in a building that receives its electricity from a source located within or shared with a dwelling; or
(d) in a garden or in or on land associated with a building where the electricity is from a source located within or shared with a dwelling.

I have seen some underfloor heating mats on a 13a flu so looking at the size I would need hopefully 13a would be ok but I will have a Google and check.

You'll need to look at the construction of your floor, determine how much heat will not be lost elsewhere, then look at the radiant efficiency of the floor surface, and determine how much of what's left of your 3kW will actually heat the room. Then do all the normal calculations for how much heating is needed for a room that size, given its aspect, window area, wall and ceiling U-values etc, and decide if it will be enough.

I was just wondering that if a have an existing supply I could connect everything myself ?

As long as you can comply with the regulations for UFH, and do all of the necessary testing, yes.

 

[ericmark]

Only ever fitted one in a bathroom. Job one was remove the floor fit drains and then special stuff to stop heat going down but that was before I took over the job.

The first job was to ensure the type was suitable had to have an earth braid around the wire or an earth mesh after the heating wire.

All the glues had to be special glues able to take the expansion and contraction and the gaps between every tile was also stipulated and again special grout.

After all this work is was a flop. In hind sight and that easy the tiles should have been smooth and black there were sculptured and cream which resulted in them retaining too much water and not liberating enough heat.

Building control insisted an extractor fan was fitted. The tiles could not replace this heat the room is cold unless the towel rail is used yet if the tiles were any hotter you could not walk on the floor.

We stopped using Hypocaust and I wondered why.

It may have worked in Rome but in Chester the under floor heating needs some other heating as well.

The simple fact that the floor could not have been any warmer and still walk on it means be it water, solid fuel or electric it simply does not work.

But the woes did not end there, the thermostat failed a few times although rated 3kW and floor was about 500W they did not last. Then the sensor went and although in a pocket and one should be able to replace is got stuck.

So although it will still work it's no longer used. OK it was a wet room not just a bathroom but once the tiles were cooled with the shower water it took 1/2 hour to dry floor with the extractor fan running it only takes 3/4 hour without the floor heating on.

Because we had to use the special screened cable we could not use the special stuff which compensates for items left on the floor. Let a towel drop off the towel rail and that bit of floor got really hot.

There is also an issue with testing and inspection. With the heating element you know it is sound as it works. But with the earth braid you need to be able to reach the opposite end of the wire to the supply to verify the earth is not broken. There was no contact so impossible to test the earth was complete. The first one laid was destroyed by the builder who used crimp connectors on the brake and glued a tile on top to hide what he had done. There was no earth after that point so clearly it does need a test point.

 

[johnad]

I wasn't looking forward to installing under floor heating and after the comments on hear and some reading online I think I will forget it and just get a good towell rad
So I'm just now looking at installing the spar bath from a plumbing centre
And I'm hopping to use the existing curcuit from the old shower
I was going to fit a FCU after the double pole switch to feed the pump as I said this is RCD protected and all the pipe work has earth bonding attached
I did plan to just make the connections myself and say nothing .
Or is this a big no no ???
I may be totally wrong but I thought you could diy like for like (after all who would know) I could have just replaced an old spar bath for a new one.
But I also understand bathrooms are a special location.

 

[deadshort]

You may want to consider a towel rail with an electric heating element for summer use? When the CH is off.

If you are confident in your own electrical ability to wire the fcu then fine. You have an RCD installed on the supply, so you're already compliant with the regs.


DS

 

[ban-all-sheds]

You might consider a dual-fuel towel rail. I did - thought it would be a great way to have it heated by electric in the summer and CH in the winter.

The element lasted about 3-4 years.

So did the next one.

Going to replace it with a sealed electric only one.

 

[ericmark]

Your question now seems to be DIY or pay for a scheme member electrician. In real terms registering work with local authority is just too expensive so DIY means the only tests and checks are those done by you.

So the question is not only one we don't want to answer but one we can't answer as we have no idea of your skill.

I involved the LABC because my mother was disabled and they were involved what ever I wanted to do and also being disabled it did not cost.

We can all look for loop holes but I would say forget Part P but instead ask yourself are you 100% certain you can install it safely and complete all the required tests?

Any risk is to you and your family and only you can assess the risk that you get it wrong. Even as an electrician I do make errors but the testing done once complete in the main will highlight errors.

Personally using a plug in tester with loop will highlight most faults when installing a socket but in a bathroom there are no sockets so really it is near impossible for any normal DIY guy to test it.

You could get an EICR done after you have finished but likely it will cost as much as getting a scheme member electrician to do the work to start with.

So sorry it's up to you. Only you can make the decision.

I don't have a towel rail which heats in the summer and it has never caused a problem for me.

 

[ban-all-sheds]

I would say forget Part P

Why would you say that?



Why on earth would you want someone to forget the idea of making reasonable provision in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury?