New storage heaters on 3-phase supply

tamste

Looking to replace old storage heaters in new house. House is on 3-phase supply and has a SMETS2 meter.

Been looking at Dimplex Quantum and Creda TSRE, but both say unsuitable for use on a 3-Phase supply.

Are there modern HHR storage heaters suitable for use on a 3-Phase supply?

Netexporter

I'm assuming it is a fairly large house, as it has 3-phase. I think I'd be looking at installing a 3-phase heat pump. Between the saving on not buying new storage heaters and the £7500 grant towards the heat pump, you'd get you money back in much lower running costs, in a reasonable period.

BarelySentientAI

Or if you want storage heaters, just supply them from only one of the phases.  Most of the equipment in your house is "unsuitable for use on a 3-phase supply".  Even rotate which phase you choose for each to keep things nice and balanced.

molerat

I believe the problem is that they need both on and off peak supplies and they may come from different phases.  If only using one phase there shouldn't be a problem.

https://help.gdhv.co.uk/support/solutions/articles/79000139250-can-i-install-a-dimplex-storage-heater-on-3-phase-supply-

tamste

Yes, it's a largish house.

Heat pump will need full installation of a wet system as the house has always been on storage heaters. This ramps up the cost significantly, thus the preference just to upgrade the storage heaters.

Phase 1 is split for use on peak and non peak with phases 2&3 only available off peak via supplier switching box. Each phase has 100A protection.

Are there any HHR storage heaters out there suitable for use on 3-phase supply?

Scot_39

You need to find out why Dimplex or your supplier say this.

In this example for instance - covering many of their models including Creda tsre

https://help.gdhv.co.uk/support/solutions/articles/79000139250-can-i-install-a-dimplex-storage-heater-on-3-phase-supply-#:~:text=No, this appliance is intended,connection to 3 phase supplies.

They are showing you actually can - as long as you do not mix the phases.

In top green tick both needed supplies come from l1 phase.

In bottom red cross - the l1 feeds peak and the l2 phase feeds the off peak.  That's when it gets to be an issue.

Go back to them quoting that example and see if they still say the same.

As the three phases are not used like an industrial unit might use if you like "proper three phase".

As they may will run 3 phases - essentially connecting phase to phase to get over 400V not 230V phase to neutral - e.g. for larger AC drive machines etc.

As internally your mains wiring will almost always be 1 phase to neutral.


Just as in large offices - you often find standard power sockets and lighting alternates off of the 3 phases as well but each device only ever sees one phase to neutral.

Edit 
Just looking at your latest home wiring description of current off peak only on 2 phases (L2 and L3) - you will I suspect then need to wire so be able to access phase 2 or phase 3 24/7 for the 24 hr live feeds for quantums in dual wired mode not single wired mode or the tsre (always dual wired iirc)  if need the off peak capacity from those phases to charge them. 

Assuming thats all you currently run to the old models / locations from those phases.

If the only thing connected to l2 restricted time switched or l3 restricted wiring is the old storage heaters.  If you wanted to scrimp on new wiring (costs and possible redecoration etc on top) the quantums could potentially be run in single connection mode (tsre's above iirc cannot) and simply amend protection cu end to make live 24/7 if cheap.  But that means always ensuring setting times to match meter times and tracking etc e.g for gmt / dst.

tamste

OK .. If understand correctly then, each phase may be just a separate circuit, so in effect 3 x single phases?

 If that's the case, then my worries should be over.??? What I think I need to establish then is which heater is on which phase supply (a couple are convectors so already have two , or potentially get rid of the off-peak switching box having a 24hr supply and have the heaters control when they charge (i.e. off peak only)?

As phase 1 is 24 hours, by "mixing phases" do you mean that the 24 hour supply should be from the same phase?

Scot_39

Well potentially 2 seperate circuits.

Restricted and live per phase.

Under modern regs each nsh is fed by its own dedicated fused spur (20A mcb ? But I'd need to check) - so a direct cable from cu to device - well normally CU to a dedicated spur socket with isolator switch then from spur socketmto device

The lower rated 24/7 live input could be pulled from local ring main - it doesn't need that point to point.

But your comnent above suggests you have no 24/7 live distributed from l2 l3 outside of CU to home to pick it up from.



And yes you will need to find out which is which.

And which may already have 2 supplies to drive fans or thermostatic / timed vent louvre controls in some cases etc.

I'd get a non contact pen and get up early one night and check each feed if not obvious from cu mcb labelling etc. Or device / socket leds 



Each new device must only be connected to 1 phase as per the dimplex support link.
So yes any device including quantums in dual mode will need 24/7 and restricted main charge from the same phase

But as wiring may be disruptive (walls, floors etc) single 24/7 live wiring mode on quantums might be an option you could consider. 
But then quantums are that bit more expensive than equivalent tsre but have advantage are hhr certified (and their is one quantum cheap rate tariff on offer at BG iirc).

Don't forget to check any other devices like hw tank or tanks immersion heaters, towel rails etc  - as they would need timers fitted if currently only relying on l2 or l3 restricted supply feed if considering that route.

I'd talk it through with your likely installer / electrician and cost the options - and ask re likely cabling routes degree of disruption etc.

mmmmikey

Without getting into the techie details there are a few different ways to achieve this and it really isn't a problem at all, you just need to find an electrician who understands both 3 phase electrics and storage heaters. Definitely a job for an electrician to ensure the wiring isn't overloaded. If you let us know where you live (town / county is fine, not a good idea to post your full address) someone here may even be able to recommend an electrician. In my part of the world it would be quite easy because there are lots of properties around here with storage heaters and lots of farms with 3 phase supplies so most of the local electricians are well versed in this kind of thing. Well worth getting high heat retention storage heaters as they are way more controllable - if budget is tight then there are always a good supply of secondhand and/or reconditioned ones on eBay and the like.

tamste

All three "phases" are 230v with L1 being split to provide 24hr and E7 supplies.
L2 and L3 are E7 only. 
Options?
Change my plans if I stay with E7 switching from all quantum to only quantum on L1 and then "dumb" storage heaters on L2 and L3 unless I get L2 and L3 split also, which could be a lot of disruption feeding the L2 and L3 24hr split supply through the house to their respective heaters.
Alternatively, go 24hr on all phases and program the quantum's to charge only in the E7/cheap period, which could be an expensive risk. HW will also need a timed switch. Can you even use E7 on single 24hr supply?
I clearly need an experienced sparky for this,

Ectophile

Having 2½ phases of E7 and only half a phase for everything else seems a bit weird.  I don't know if Quantum heaters would cope with having the night supply on one phase and the permanent supply on another.

If you do get an electrician in, it may be worth checking who owns the contactors that are switching between day and night.  If they are yours, then the electrician may be able to wire it up more sensibly.