Elnur HHR Storage Heater Review, Smart Controls & Storage Efficiency Tests

mmmmikey

Hi,
I've just bought a used Elnur ECOHHR20 storage heater off eBay to replace an electric radiator in my hall way. I've also made a control box to connect it in which gives it smart features. It's proving to be an interesting project so I thought I'd share details here. This post is a bit of a mixed bag, including a review of the heater "out of the box", information on the control box, and storage efficiency tests.
Firstly, as far as a review the unit itself is concerned I have to say I'm impressed with the quailty of manufacture. For some reason I had thought of Elnur as being a cheap and cheerful brand, but that doesn't seem to be the case at all. All the different parts of the case line up properly and fit together well - both the bits you can see on the outside and the internals. The fan is quiet and smooth running and the controls are easy to operate. Even the manual is impressive and simple to follow. The heater can be wired in to use either single or dual wire circuits and set up to use with pretty much any time of use tariff, be it a so-called legacy TOU tariff such as Economy 7 or a smart TOU tariff (Octopus Tracker in my case now, probably to be replaced with Octopus Agile over the winter). So an easy 5 stars out of 5 from me for the unit itself.
The smart control box allows the input/charging and output/heating to be controlled by Home Assistant. On the input side, it's just a question of connecting the unrestricted supply directly to the mains and connecting the restricted supply to a high-power Sonoff smart switch (which also monitors the energy usage). There are also a couple of menu options to tweak on the Elnur control panel. The input times can then be easily controlled via Home Assistant to match the TOU cheap times. Controlling this via Home Assistance has a few advantages: it's easier to set up the schedule this way, the schedule can be altered dynamically (e.g. different charge times each day if your using Agile), if you have more than one heater you only need to set up the schedule once, Home Assistant also monitors the energy usage.
The output/heating side is slightly more involved. A relay board is used to operate the switches on the control panel. This involves soldering connectors to the control panel circuit board - very easy to do but would invalidate the warranty on a new unit. Home Assistant can then be programmed to switch the heater between the Comfort and Economy output settings by operating the switches. By setting the Comfort setting on the storage heater as high as it will go and the Economy setting as low as it will go, switching between the two modes has the effect of turning the output on and off and allowing it to be controlled with a Home Assistant thermostat. Doing this has several advantages. The temperature sensor that Home Assistant can be placed anywhere in the room to get the best representation of the room temperature. The hysterisis is adjustable making it easy to accurately control the room temperature within a few tenths of a degree. The schedule can be as elaborate as you want it - a programmable thermostat on steroids. The heater can be operated across the internet - e.g. heat up the house before getting home. The schedule can be varied automatically, e.g. switch the heaters on earlier if it's cold outside.
The input side of the control box just works.
I have a minor issue with the output side and I'm tweaking it now. Sometimes the unit doesn't switch on when the thermostat tells it to. Should be easy enough to fix - just need some colder weather as June isn't (normally!) the ideal month for testing
Finally, I'm now getting things set up to see how much energy the heater looses from one day to the next with the output off. I'll fully charge the heater tonight, leave the output controls off and then charge it up again tomorrow night. Whatever I put in tomorrow night will replace what's been lost. I'm expecting this to be a lot less than an old-fashioned storage heater but don't really have much concept of the numbers. I'll post an update once I do. The practical questions this answers are: (1) is there an advantage to only partially charging the heater on cooler days to minimise these losses (2) will there still be plenty of heat for the evening.
A long post - hope it is of interest to someone....

FreeBear

mmmmikey said: Home Assistant also monitors the energy usage.

How are you measuring energy consumption - A current clamp on the cable, or just calculated from the period the NSH is charging up ?

mmmmikey

FreeBear said:

mmmmikey said: Home Assistant also monitors the energy usage.

How are you measuring energy consumption - A current clamp on the cable, or just calculated from the period the NSH is charging up ?

Hi, I'm using a Sonoff POWR320D to measure the energy consumption and using Home Assistant (alongside Node Red, InfluxDB and Grafana) to collect and display the data. Home Assistant is also switching the POWR320D output on and off which is what is controlling the restricted supply to the storage heater.

FreeBear

mmmmikey said: I'm using a Sonoff POWR320D to measure the energy consumption and using Home Assistant (alongside Node Red, InfluxDB and Grafana) to collect and display the data.

Sweet ...

bob2302

mmmmikey said:

The heater can be wired in to use either single or dual wire circuits and set up to use with pretty much any time of use tariff, be it a so-called legacy TOU tariff such as Economy 7 or a smart TOU tariff (Octopus Tracker in my case now, probably to be replaced with Octopus Agile over the winter). 

There was no point in buying this unless you are definitely going off Tracker. 

mmmmikey

bob2302 said:

mmmmikey said:

The heater can be wired in to use either single or dual wire circuits and set up to use with pretty much any time of use tariff, be it a so-called legacy TOU tariff such as Economy 7 or a smart TOU tariff (Octopus Tracker in my case now, probably to be replaced with Octopus Agile over the winter). 

There was no point in buying this unless you are definitely going off Tracker. 

Doh - you're right of course - I meant to say Octopus Flux

worlestone

That sounds like a very interesting project, not that I understood a lot of it, but living in a rural property with no gas, just E7 and a bunch of older Dimplex XLN NSH's. Running newer Lot 20 heaters isn't really an option due to the difficulty/expense we'd have to go to in wiring the unrestricted supply, but interested in the control box and single supply option.  

How's it going as we go into autumn?

mmmmikey

worlestone said:

That sounds like a very interesting project, not that I understood a lot of it, but living in a rural property with no gas, just E7 and a bunch of older Dimplex XLN NSH's. Running newer Lot 20 heaters isn't really an option due to the difficulty/expense we'd have to go to in wiring the unrestricted supply, but interested in the control box and single supply option.  

How's it going as we go into autumn?

Hi, thanks, haven't needed to use them yet, at this time of year the log burner suffices with just a small amount of extra heat in the bedroom and bathroom. Co-incidentally, I've just added "check heaters" to my list of jobs for the week :-)