Space heating question

pinnks

I can't find a thread on this, so here goes.


I have an Immersun and now that I have the 5.25kWp on the roof find we get the majority of our hot water needs (100% in the summer months and about 60% or so over the winter) from PV. We need to stick about 2kWh into the immersion each day.


At this time of year on good days - 18kWh today - we have plenty of spare leccy. I have put a 2kW oil radiator onto the second output of the Immersun and it works well to help take the chill off the room but the radiator thermostat turns off quite quickly and it of course cools down quite quickly. Today it put about 6kWh through the Immersun, so about 4kWh to the radiator. I could probably have pumped another 5 or so kWh in its direction if it could have coped which would have meant the heating could have stayed off for a while longer.


My aim is to find something that looks good (not a traditional storage heater then), can soak up whatever the Immersun can throw at it (max load 3kW resistive load) and will hold its heat reasonably to act a bit like a storage heater. This should mean we can turn the gas CH off a month or so earlier and back on a month or so later with the evening chill taken off the living space - bedrooms are getting to the point at this time of year where heating is not needed. We already turn it off for nearly 6 months - 7+ would be good.


I found a German designer storage heater that looks exactly what I need (subject to checking it would work with the Immersun). Various shapes and powers but the biggest is 2.6kWh I think and the are all only 7cm deep, so look great but it costs about £1200, so would never repay the investment.


I did think of polishing, lacquering an old immersion tank and getting it oil-filled but would be a bit worried about expansion and overall safety but a polished copper tank could look cool standing in the corner of the room.


Anyone gone down this route and/or have any ideas?


Gary

Andy_WSM

Hi Gary,

10 years ago I fitted my conservatory, living room, kitchen & hallway with electric underfloor heating.

I love it, BUT...it is expensive to run, so I have since fitted a heat pump & radiators, which is very cheap to run - however - this gave me an idea to soak up the spare power and I fitted a diverter to send the excess to the underfloor heating - and have a switch over relay, so when that is satisfied it diverts the excess to the immersion.

The last couple of weeks it's paid dividends! I've got the benefits of the underfloor heating back that I like so much, it's taken a lot of work away from my heat pump (a good thing for it's longetivity) and it's reduced my heating costs. Win, win, win!

The conservatory floor is still "as normal" and can be seen switching on from time to time on my wattson dashboard ( http://wattson.energyhive.com/dashboard/AndyW ) - the parts of my graphs where consumption closely matches production is the 4kW or so of floor soaking up the excess PV in the rest of the house.

I know you don't have UFH you can utilise, but could you add a second oil filled radiator somewhere else perhaps? The diverters are generally built to withstand up to 16A of load - which is 2 * 2kW heaters (roughly). What it means is that if there is 2kW spare, then approx 1kW will go to each one. If they are in different parts of the house, then hopefully the thermal mass of the house will be able to soak up some of the surplus.

The problem with using normal heaters is that you risk over heating the house whilst attempting to benefit from the free power! Other than "proper" storage heaters then there isn't a lot you can do about that - and those German clay filled things are not a lot different to our cheap oil filled radiators in all honesty.

pinnks

Thanks. Pretty much where I have reached in my thinking. I do have UHF in my two bathrooms and glass electric rads too, so could hook then up but that is not where I want the heat of course...


I had thought of a second oil rad on the relay circuit but the Immersun states the max load is 3.2kW and you can't guarantee they are not both on at full whack at the same time.


I could upgrade to the Mk 2 diverters which can switch 3 devices in sequence, or daisy chain another Immersun and get a total of 5 switchable devices but that adds significant expense.


I could also add UFH somewhere downstairs but to be honest of I were to go to that upheaval I would probably do something like the Schutter low temperature water system where you only replace the screed.


Looks like my cunning plan to find an easy way to mop up excess at 4his time of year for living room heating may not be economically sensible...