UFH upstairs - alternatives?

[PeterW]

1 hour ago, JSHarris said:

I've used mine in CU housings that aren't being used as CUs, because they are often the cheapest way of getting a DIN rail wiring box.

 

No comment as to where I got my idea from ..!!

 

Keeping the main switch to isolate the power to all the timers etc but the whole of the heat system including pumps etc uses around 900w when it's all switched on. That's protected by a 10a RCBO. 

 

The only one that is not part of that is the immersion circuit which is SSD operated so isolated and fitted in another box. 

[Jeremy Harris]

I've just counted up and I have four CU housing that aren't used as CUs! 

 

There's the heating/cooling controls one you've probably seen, plus another in the water treatment building that has the borehole pump and filter controls, timer etc, plus two IP68 CUs that I converted into home made EVSEs (Electric Vehicle Supply Equipment).  The two EVSEs have the DIY electronics that does all the control signalling between the car and the charge point, plus houses the DP contactor that isolates the charge lead if the car commands it or if the car charge plug latch is operated (makes sure the lead to the car is never live unless it's latched into the car and the car has sent the "power on" signal to the EVSE). 

[Steptoe]

As an aside,

If you have a CU being used as a CU, ie, main switch and MCB or RCBO feeding circuits, then you can't just fit a generic time clock or contactor in it, you are not allowed to mix and match.

in real life, is it a problem,?

Not that I can see of,

Legally,? It's a massive NO.

It's to do with a manufacturer only certifies their cu for use with their products, so in reality, unless it's been certified for use with anyone elses product then you are not permitted to fit it, it could be an insurance get out clause.

And will be picked up on any future EICR by a competent person,

In other words, if you fit a Hager CU you have to fit a Hager time clock/contactor, same with most other manufacturers.

 

[Steptoe]

2 hours ago, JSHarris said:

I've just counted up and I have four CU housing that aren't used as CUs! 

 

 

So,

That'd simply be 4 DIN rail enclosures then,?

[Ferdinand]

14 hours ago, PeterW said:

 

Yes but tbh they are planned to be coming on an hour in the morning and one in the evening. Boost will be via button on the CU but it's accessible anyway. 

 

It looks like a good cost shaver in the appropriate circs. 

 

Thanks all.

 

[Ferdinand]

4 hours ago, recoveringacademic said:

 

Mmmm, lovely. Except those that were from the compost heap. 

 

Is the Handbags for Barbie (or Ken) factory set up yet?

Edited February 9, 2017 by Ferdinand
Not inclusive enough

[Barney12]

16 hours ago, joe90 said:

Cool, does this not mean that if you want to override the timings you have to go to the CU ? I installed electric UFH fir a customer that had a programmer with everyday settings but an override button that allowed an instant 1hour "on now" facility which is what I fancy. I can't remember the make. 

 

I've been pondering this point (in the middle of the night hence the time of this post). I think my solution would be to locate the timers for the UFH and towel rads in a separate enclosue upstairs. In our case in the wardrobe back wall in the dressing room. This means local control is more accessible and also has the minor benefit of reducing cable runs.

 

 For our sparkies........

 

I assume some form of DIN rail enclosure fed by an RCD from the main CU is an acceptable solution under the regs?

Would the remote DIN rail enclosure need local isolation (DP switch)?

[PeterW]

7 hours ago, Steptoe said:

As an aside,

If you have a CU being used as a CU, ie, main switch and MCB or RCBO feeding circuits, then you can't just fit a generic time clock or contactor in it, you are not allowed to mix and match.

in real life, is it a problem,?

Not that I can see of,

Legally,? It's a massive NO.

It's to do with a manufacturer only certifies their cu for use with their products, so in reality, unless it's been certified for use with anyone elses product then you are not permitted to fit it, it could be an insurance get out clause.

And will be picked up on any future EICR by a competent person,

In other words, if you fit a Hager CU you have to fit a Hager time clock/contactor, same with most other manufacturers.

 

 

So what if I have a MEM CU that's not being used as a CU, just to house 4 time switches and a couple of relays and a contactor ..??

 

It has no MCB or RCBO in it, just control gear ..?? I'm also assuming it doesn't have to be metal clad either ..?,

[Nickfromwales]

After the CU it simply becomes 'fixed equipment'. Ideally it should have local DP isolation ( 20a DP switch to the side ) for disconnection. 

 

Edit : Maybe an din mounted 80a isolator would tick that box? 

[Jeremy Harris]

2 minutes ago, PeterW said:

 

So what if I have a MEM CU that's not being used as a CU, just to house 4 time switches and a couple of relays and a contactor ..??

 

It has no MCB or RCBO in it, just control gear ..?? I'm also assuming it doesn't have to be metal clad either ..?,

 

First off, CUs do not need to be metal to meet Amendment 3, the new regs just say that they have to be made of fire resistant material.  The manufacturers have decided to switch back to metal because it's the easy way out, so everyone is using metal CUs to meet the Amendment 3 requirement, but there are reinforced composites that meet the fire resistance requirements too, so I wouldn't be surprised to see compliant "plastic" boxes available before long.

 

If a CU box is not being used as a CU, and just has a protected feed coming into it with the box just housing control gear, then that is fine, as far as I can see.  I double checked this (admittedly under the last issue of BS7671, not the current one) when I did something similar and there was no problem at all doing this.  Not only did our electrician sign it off, but the building inspector also had a good look at it, as he was interested in what I'd done.

 

The problem only arises if you include primary circuit protection in the same box and rail as other control gear.

 

[ProDave]

The new Amd 3 rules also cover "switchgear" enclosures. I am sure your box with timers would be classed as such.

 

But of course you installed them before 1st December 2015 didn't you?

 

Re UFH upstairs.  fit a dummy thermostat on the wall, have your completion certificate done in summer, and nobody will ever know there is no upstairs UFH 

 

[Jeremy Harris]

23 minutes ago, ProDave said:

The new Amd 3 rules also cover "switchgear" enclosures. I am sure your box with timers would be classed as such.

 

But of course you installed them before 1st December 2015 didn't you?

 

Re UFH upstairs.  fit a dummy thermostat on the wall, have your completion certificate done in summer, and nobody will ever know there is no upstairs UFH 

 

 

 

Thanks Dave, I only have a copy of Amend. 2 here, so wasn't sure.  In my case the installation certificate was all signed off in 2014, well before there was a hint of the "fire resistant box" requirements.

 

The funny thing is that CUs were very commonly made of metal years ago, in fact the one in our old house is, so we're just reverting back, really.  I can fully understand why the fire resistant materials reg has been made, too.  With CUs now full of RCDs, MCBs  and/or RCBOs, plus the higher peak electrical demands imposed by a lot of modern kit, there has to be a greater potential for over-heating than there was.

 

I poked my thermal camera at our all RCBO CU and it's definitely warmer than the surroundings by a couple of degrees.  Not enough to be noticeable, but enough to show on a thermal image.  There were no faults anywhere, I checked out of concern when I found out it was slightly warmer than the wall behind it, it's just the very even heat build up from all the RCBOs, as they do seem to consume a tiny bit of power all the time.  I did the same exercise on our old metal wired fuse CU and it's at ambient temperature, not even half a deg warmer than its surroundings.

Edited February 9, 2017 by JSHarris

[Steptoe]

5 hours ago, PeterW said:

 

So what if I have a MEM CU that's not being used as a CU, just to house 4 time switches and a couple of relays and a contactor ..??

 

It has no MCB or RCBO in it, just control gear ..?? I'm also assuming it doesn't have to be metal clad either ..?,

If it only houses control gear then its no longer a CU,

As @Nickfromwales points out, its now merely a din rail enclosure, 

You wouldn't necessarily need direct isolation , but would need to label it up as having 2 sources of energy, ie, the control signal, and the power supply, so requires isolation at 2 points, or at the main switch. Whichever is applicable, 

If you want to use one switch to only isolate the enclosure it would require enough poles to isolate the control cables and the supply cables. 

[underfloorplumber]

@Redoctober 

There are multiple ways to have an underfloor system fitted upstairs. You can fit between solid wood joists, they just need to be notched out. The joists with the metal webbing can't be notched so you can fit a batten on top of them to fix a spreader plate to or you can fit an overlay system if you have a deck already down, or indeed fit a plate to the underside, that though is a pain in the erm.... neck. Let me know if you want any further advice, I'm happy to help.

[Redoctober]

@underfloorplumber Many thanks and I will certainly bear that offer in mind - By the way, welcome to the forum. Perhaps you could introduce yourself via another thread and let this "crazy of people" know you are out, so to speak! Enjoy.

[JohnW]

I can see the appeal of electric UFH in bathrooms to take the chill of the tiles.

I'm planning to have wet UFH upstairs in a concrete screed on hollow core slabs. It'll be heated using the heat from a thermal store (heated via ASHP).

 

With this setup will I be able to lay carpets upstairs or will the heat not be able to get through it?

 

[Declan52]

I have carpets over 3 rooms that have ufh and it works fine as long as you get a low tog carpet and underlay. Don't take the sales reps word the carpet and underlay is suitable check the documentation before you buy.

[Bitpipe]

On 14/02/2017 at 10:23, underfloorplumber said:

@Redoctober 

There are multiple ways to have an underfloor system fitted upstairs. You can fit between solid wood joists, they just need to be notched out. The joists with the metal webbing can't be notched so you can fit a batten on top of them to fix a spreader plate to or you can fit an overlay system if you have a deck already down, or indeed fit a plate to the underside, that though is a pain in the erm.... neck. Let me know if you want any further advice, I'm happy to help.

 

We have a wet UFH system on our ground floor, which is suspended timber construction (as we have a basement).

 

Used alu spreader plates stapled to the top of the joists, however we have Pozi joists so notching was not an option for the loops that cross over the joist (every other loop) - after a bit of head scratching we realised that the floor deck we were laying on top was 22mm thick and the pipe plus clip was only 16mm so we just left out a strip of floor deck where the pipes crossed over the joists.

 

The final floor was resin laid on cross laid ply (9mm & 12mm) so we just needed to be be careful as to where screws went when laying that.

 

Before insulating & boarding the ceiling under the floor, I spent a day stapling the undersides of the spreader plates to the OSB deck above to ensure they met as tightly as possible.

 

All told, there is over 50mm of buildup between the pipes / plates and surface (22mm OSB + 9mm ply + 12mm ply + 4mm rubber crumb mat + 6 mm resin) so the response time is slow but the heating works fine (on the odd occasions it comes on).

[JohnW]

On ‎07‎/‎02‎/‎2017 at 18:49, Alphonsox said:

Electric UFH in the ensuite and bathroom. We have wired for electric radiators in all bedrooms.

@Alphonsox can you recommend a make of electric underfloor heating?

[Bitpipe]

2 minutes ago, JohnW said:

@Alphonsox can you recommend a make of electric underfloor heating?

 

I bought the cheapest mat kits off eBay and they worked fine - you can bin the controllers they supply by default and get something nicer. They tend to come with primer, rollers, conduit, tape etc.  Got the 6mm backer boards and fixings from UFH superstore.

 

Mats are ordered by size and can be cut to go around obstacles, you only need heating where you would stand so not under sinks, baths, WCs etc. We went for the lowest wattage wire (100W I think) and it has been fine.

 

Make sure you get a multimeter to check  (& remember to record) the voltage of each mat when still wrapped up, after unwrapping and after laying - the alarm units are good also for peace of mind during fitting.

 

Once the mats are down (and supply / stat cables pulled through to stat back box), you make up the floor level to just over the top of the wires with latex and then tile on top of this.

 

Spark then wires them up as second fix, you need a separate fused connection for each mat.

[Guest Alphonsox]

1 hour ago, JohnW said:

@Alphonsox can you recommend a make of electric underfloor heating?

 

We did the same as @Bitpipeand bought a cheap mat kit from ebay, (http://www.ebaystores.co.uk/warmstarltd).

The mat was laid by our tiler, and I connected the controller and electrics -  all pretty simple IIRC.

[PeterW]

Same company here

 

[Bitpipe]

38 minutes ago, Alphonsox said:

 

We did the same as @Bitpipeand bought a cheap mat kit from ebay, (http://www.ebaystores.co.uk/warmstarltd).

The mat was laid by our tiler, and I connected the controller and electrics -  all pretty simple IIRC.

 

Yep, that's who I used. No complaints.

[JohnW]

Great - Thanks