Ditching gas, going electric immersion only, a wee project

Reed_Richards

Had you considered a fatter radiator instead of fans (a quieter solution)?  I mean the triple panel triple convector type 33.  These are notably fatter than standard radiators but behind the couch you probably would not even notice.  The amount you spent on those fans could have gone a long way towards the cost of a new radiator.  

Solarchaser

Yeah thats a fair point, and no I hadn't, as I've never seen triple panel rads.
That would certainly be a larger heat source, but I'm not sure it would have helped as much as the fans could (maybe) as it would still suffer from the lack of airflow due to the couch, and thats not moving.

I'm a sucker for new/good technology and the fans seem like a gimmick, but at the same time I can see a fair bit of thought has went into them.
With a heat sensor like a 301 switch I could make up something very similar for less than half the cost, but I figured I'd give the real deal a try before dismissing.
It's is helluva costly for a half dozen fans, but as I've just fitted them and checked 3 times they are actually on, they definitely are not loud.
Perhaps I'll be able to hear them in a silent house, but definitely can't hear them just now.

If they don't work, I'll ebay them, and get a thicker rad maybe, they seem to go for 90% of their new price when sold second hand.

The major bonus they have over a new radiator is they literally took 30 seconds to fit, and nothing needed draining.

Reed_Richards

Solarchaser said:

The major bonus they have over a new radiator is they literally took 30 seconds to fit, and nothing needed draining.

Solarchaser said:

I've already removed it, cleaned out the little sludge that was in it and fitted insulation foil behind it to reflect the heat better, 

I figured that if you could do all that with your current radiator then fitting a new radiator would not present much of a challenge to you.

Solarchaser

I wouldn't say a challenge, as its straightforward,  but it does require draining system then repressurising plus the actual manhandling and messing about with valves. 

I'm not saying its very involved as its not, but its definitely not as quick as clicking in some magnetic fans.

I should also say the removal and cleaning was in the summer, and I wouldn't fancy being a day without heat mid winter.

OK OK, I'm being lazy, I admit it 🙌

markin

Do you use every minute of the 3hrs to heat the tanks, could running the heating 10min an hr give the house a boost and more storage in the tanks.

Not sure you should be letting the night time temps fall below 18c, The system will just have to work harder to get back up and then need a bigger daytime top up. Smart TRV could be used to keep the bedrooms cooler?


A heatpump could go at the bottom of the garden and be completely hidden by a green fence.

Solarchaser

Every minute of the 3 hours is used to heat the tanks.
The big hit to the tanks, or the biggest drop in temperature is when the water in the radiators is cold,  and the tanks have to heat it all up to heat the radiators, so although I haven't tried it, I'd be confident that running the CH for 10 mins every hour would be more energy intensive than just running it when required for set times during the day.
It takes between 10 and 20kwh to heat from cold, but roughly 3kw an hour to maintain temperature.

This week I've had to reduce the heating to the tanks, I was doing approximately 12kwh extra over the last 3 weeks outside of the 3 hours off peak, and on certain days adding another 6kwh or more to keep the house warm.
Since the start of the week I've been backing that off about 3kwh every other day.
Yesterday I added only 3kwh in outside of the normal 36kwh of off peak, however 2 hours into my 3 hour off peak I was finding 2 of the heating elements had reached max temp and were cutting off.

I'll keep adding in 3kwh a day for the moment, but the weather being above zero has made a big difference. 

Minor observation, noted a couple of days last week that it was colder at night while tanks were hot, CH was on, but not running due to thermostat having clicked off.
Thermostat is in hall above electric box.
Running 22kw through electric box meant that it was generating quite a bit of heat itself, and that heat was fooling the thermostat. 

I have 4 x 3kw elements going through a 50A trip, and it tripped on Wednesday.
It had done it a few weeks ago, which I put down to just nuisance tripping, but I've went on the standard 3kw =12a, so 12kw is 48a, this is handy shorthand when doing quick checks, but ultimately false, although most of the time we take 4a per kw, that assumes a mains voltage of 250v, and thats not what it is, and not what the element internal resistance is built on.
Mains voltage of 240v with 12kw actually means a draw of 50a (P=IR, power (watts) = current x voltage) and so I'm running the circuit for 3 hours at 50a through a 50a fuse, no wonder it tripped! I dont want to put it through a larger trip, so instead I'll take the feed for 1 element from a totally different circuit on my consumer unit.
The EV circuit is stand alone off the CU and also with a 50a trip, but will supply less than 30a for EV charging, and has a spare 16a trip, so I'll be using that. The advantage of the SSR's switching the elements on and off means I can still have all of the control on the one circuit, and just the dumb power coming from outside that circuit for one element.

Some teething problems are unexpected,  and some are just stupidity.

As for the fans fitted to the livingroom radiators.... well this week the temperatures have been above zero, so its an unfair comparison, the livingroom has definitely felt hotter, but I can't say if that's the fans or the lifting of outside temps. 
I can definitely say that they are silent running, even in a totally quiet house I've had to be right up to the radiator and listening intently to confirm they are running.

1961Nick

The voltage measured at the immersion heaters is probably around 230v so 12kWh is probably nearer 52 amps. That's going to get a 50 amp breaker pretty hot over a sustained period.

Keeping the rads hot during the off peak is effectively increasing the size of your thermal store so that makes sense.  

Solarchaser

Well only if I have more kwh of power than I have of storage, right now thats not the case

Edit. Back to the lux discussion of yesterday,  the Lux shows a constant 245V so should be better than 230 at the elements 
Edit 2. 241v at the off peak, I assume drawn down by my excessive current use

1961Nick

Solarchaser said:

Well only if I have more kwh of power than I have of storage, right now thats not the case

Wouldn't Intelligent Octopus with 6 hours off peak work better for you? I assume that you've got a cheaper deal than that at the moment & that's why you haven't changed, but it might be worth running the numbers again based on your experience over the cold snap.

Solarchaser

My colleague running intelligent octopus says they ask for the charge of the car and the limit of charge suggesting they want to select when to charge, I cant really Do that with the heat as I'm running off specific timers.

I suppose if they spoke to smart plugs etc it could be doable. 
But yeah until mid Feb I'm on 4.5p for 3 hours, so I will really start looking in earnest come mid January