Replacing old storage heaters

tamste

I live in an off grid (i.e. no gas) home which is heated using storage heaters which are approximately 40 years old. I am intending to replace these with modern storage heaters to have better control and reduce bills.

Modern heaters seem to be either "smart" (SSH) or high heat retention (HHR). The HHR versions are significantly more to buy cost wise, but apart from improving the EPC rating (not my chief driver) is the additional cost worth it?

EssexHebridean

HHR are a complete game changer compared to the old style ones - they are far more akin to central heating due to the extra controllability. A single one installed in the hallway of our old flat made the difference between us being regularly fairly chilly, and being perfectly warm enough most of the time. It also reduced our electricity spending due to us being able to make far better use the the heat produced by having it released when we wanted it, rather than throughout the day. If we were ever to return to storage heaters I would be looking straight at Dimplex Quantum again. 

Gerry1

You have to work out the energy savings from not wasting heat when not needed (e.g. overnight and if you're out during the day, maybe 15-20%?) versus the time you expect to stay in the property.

Scot_39

As above the main advantage of HHR NSH Panels is unlike the early models - they wont lose a lot of their heat - when you don't necessarily need it.

Oh and a lot less tinkering as the weather changes - the best modern NSH also adapt charge taken - based on actual need - not like my old - where set the brick temp charge - and then struggle with cold / heat for days if get it wrong in advnace.

Dimplex quote 27% advantage over older conventional NSH hear - but the devil will be in the detail and other HHR NSH Panels are available.

https://www.dimplex.co.uk/en-gb/company/news/mythbusters-quantum-vs-night-storage-heaters

If on legacy tariffs - like E10 in my case - with split off peak zones - check supported - one - was it the Elnur Ecombi iirc didn't support my 3 off peak times per day - so I discounted them - when looking at prices - but what I thoufght was a fault turned out to be a  MCB not the NSH itself.

There are non HHR panels that have much the same degree of contralability as the modern HHR panels - in terms of programmability - time / temperature profiles etc - and fan assist - to deliver higher peak power - or smart linked if you want mobile control whilst away from home

Quantums were not cheap - the new RF's at the time even less so - so I had a look at Creda TSREs to save a few £100s - but in end stuck with old (my their getting old and failing - ended up a faulty MCB overheating and tripping).  As thought those would be ok for halls (just to give a more constant base heat 24/7 to avoid damp etc)

The other thing to note - is if your old NSH are single fed from off-peak / restricted time only - circuit - the new ones - apart from Quantums (which can be single wired - but to 24/7 live not restricted ) from the ones I checked - have to have both a 24/7 live and restricted feed.

So get an install quote - not just a supply price.

And to be honest it is probably safer to have the quantums dual wired. As otherwise you have to set the charge times to match exactly your meters off-peak times on the quantums - summer and winter etc.

But if buying much more than a 2-3 quantums - have you considered stretching to an ASHP with grant (wet) or central air (grant ?) - or per room reverse air conditioning (no grant) - to take adavantage of higher COP efficiencies - which could be even cheaper to buy run over the long term.

Have a flick though the ASHP section at top of this forum section.

tamste

Thanks for the replies.

I had considered ASHP, but as I pay 30-40% of the price for E7 electricity which the NSH's run off vs mainly peak at 200 - 300% efficiency, electric prices work out in my case, slightly in favour of the NSH's, and I won't need to put a wet system in .. just direct replacement with nearest output value.

What I was trying to establish is whether the currently available HHR NSH's are worth the extra money over SSH NSH's as there is a significant price difference. Elnur HHR's & SSH's, and Dimplex Quantum's are able to be wired to a single 24hr supply, which is probably the way I will be going anyway. 

HHR's have a heat retention value of ~50% vs SSH's of ~43%

Gerry1

If you run clever NSHs from a single 24h supply it's critically important that:-

• You are fully familiar with how to program them; and

• You know precisely when the E7 rates are operational.

Get anything wrong and it could prove very expensive.  Pitfalls include:-

• E7 times not as expected;

• Two hours of peak rate in the middle of the night in some regions;

• GMT/BST times out of kilter; and

• Top up heater (Balance element) kicking in automatically at day rate, unknown to you.

Make sure there's a switched E7 outlet with a neon indicator that you can see at a glance.  That's the only way to be sure, and it's also useful to know when to use high power devices such as electric showers.

tamste

Understand fully that with a single 24hr supply I would need to ensure they were programmed correctly for the TOU tariff.

Only looking at 24hr unrestricted supply as current heaters are on two different phases, only one of which (L1) is split to a 24hr supply. Those on L2 would therefore need a 24hr supply feed from L2 to avoid any phase change issues which may need the walls channeling to achieve, which I don't want, unless I have misunderstood that they need both the E7 and unrestricted supply from the same phase?

Scot_39

Your correct - e.g. according to Dimplex they have to be on same phase e.g.

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,the potential of phase crossover.

Phase to phase for instance creates a potential 400V live to live vs 230V live to neutral inside the case.  One phase can also fail whilst other maintained.

tamste

The old storage heaters are currently switched through the suppliers contactor box to charge during the E7 period, which is essential with the old heaters, but the new ones can have a single 24hr feed, which makes wiring them easier, at least for the ones on L2 where I don't currently have a 24hr supply (only from L1).

Would it be better to
1. Take a 24hr split off L2 and rewire the 24 hour supply in the rooms with heaters on L2 to the L2 split
2. Dispense with the contactor box having all heaters on 24hr supply. I am fully aware that with this arrangement, I will have to program the charging times carefully for each heater. If this route, how would one go about bypassing / removing the contactor box .. who needs to do this?

Not intending to do this myself, but just researching to be better informed when I get the installation sparky out.