Ditching gas, going electric immersion only, a wee project

Solarchaser

Solarchaser said:

Received my octopus bill for mid November to mid December and so compared it to last year's bill.
2021 bill was 715kwh
641 off peak and 74 peak at a total of £47
Gas for the same period was 1500kwh @3.6p so £64
So £111 combined

This year its 1940kwh
1700kwh off peak and 240 peak
No gas, so total is £118, so looks like a increase of £7 over last year

However if I was still on gas, the gas bill would have moved from 3.6p to 10.3 so the £64 would now be £154 which would have taken me to £201, and in that respect I've saved £83

A bit of positivity

Got my bill in for mid December to mid January. 

Jan 21's bill was
Gas1765kwh £51
Electric 783kwh £58
Total 2548kwh = £109

Jan 22's bill was, (well I don't know exactly as the bill is December to Feb for both gas and electric, so I'll just half both of them)
Gas 1615kwh gas
Electric 569kwh off peak 60kwh peak
Total 2248
Elec £42 and gas £69 = £111
Gas now would be £166 so total would be £208

Jan 23's bill is
1818kwh off peak 382kwh peak
Total 2200kwh = £143

So as with last month, looks like an increase of £33 in comparison with the previous year, but when compared with using gas at its current price its a saving of £65

That's basically if I changed nothing else, my tarrif runs out in a months time, whereby my electricity prices will increase more than double,  in the last two years the gas went from 2.53p/kwh to now would be 10.3p/kwh, so a 4 fold increase.
It was the increase in gas price to more than the off peak electric price which convinced me to push the button in april/may last year.

Solarchaser

Solarchaser said:

I noticed last night that 2 hours after the heating had switched off that the first radiator in the circuit upstairs and the first one in the circuit downstairs were actually warm to the touch, 2 hours later is bad, I confirmed with thermal camera that floor loops were still warm also that means that even with the double check valves and loops I have in the system, that when the pump kicks off, there is still a good amount of water moving around the system drawing heat from the tanks, and that will certainly be negatively impacting my overnight temperature drop.

The only way to stop this dead seems to be using motorised valves in supply and return to the central heating circuit, which I will look to do in the spring when adding another tank.

......


When I add in motorised valves to supply and return lines for central heating that will stop dead any water flow that is simply happening due to the increased mobility of a circuit under pressure. (I could probably drop the pressure in the circuit to zero and that would stop the mobility,  but I think it would also cause a considerable increase in the noise of the central heating when running as there would be an increase in pump cavitation and general air in the pipes).

I thought it would be worth commenting on this again.
I have temperature sensors on the supply and return to the central heating circuit at the tanks.
Most of the radiators in the house are traditional panel radiators with the normal corrugated look to them.

I have 3 of the more "modern" or "stylish" type like this:-

Two are horizontal bars, and one like this, vertical.

The two horizontal bars are the first in circuit on ground floor and upstairs.

An hour after heating is off, all of the traditional radiators are cool if not cold to the touch.
The horizontal ones are still warm.
I took this to mean I was still getting circulation after the heating was off, and so my double check valves were not doing the job they were bought for, however... over the last week or so I've investigated this a little more and found that within an hour after switch off the supply temperature in the pipes has returned to 30C which is pretty much what it sits at when not being used, and the return pipe is around 28C, so there is no circulation of water happing after switch off.
I noted in my Flir camera that the pex loops in the floor were still warm, however the heat is travelling through 20mm floor boards, a flooring insulation layer and then 8mm of laminate, and so it make sense that this will take a bit of time to show heat and also take a bit of time to return to cool after switch off.

IR cameras don't like reflective surfaces, so it wasn't useful to use mine in relation to the flat panel radiators as they are silver.
If they were white I'd have figured this out sooner.
The pipes leading to the radiators are cool or even cold to the touch say 30 mins after switch off, the radiators are warm, the tops are hot.
Of course being a normal sized human I don't routinely check the bottom of a radiator, and I didn't.
I felt the top, it was hot, I assumed the whole radiator was hot.

So in short the central heating appears to be working fine and water flow is indeed stopped when the pump stops.
Water going to any part of the circuit would need to go through the pipes with the temperature sensors on them.
Good news that I don't need more motorised valves and the check valves are working.

So why are the radiators still hot?

Well I think it goes back to a short discussion with @70sbudgie earlier in this thread around the reason that traditional radiators have ribs or fins on them, I've always thought if them as a heating to provide more surface area for heat shedding, and 70sbudgie suggested they were to break up laminar flow of air.
What these modern stylish flat panel radiators don't have, is fins, and so both their surface area and potential for breaking up laminar flow is largely reduced.
I'd assume as well that because the panels are essentially identical sized boxes, one on top of the other, that airflow around the bottom one will be decent, but as it gets to the top there won't be much air running against that flat panel, and obviously the hotest water will be at the too.

Or at least that's the theory I've came up with after realising the pipes from the central heating and to the radiator were not hot as I suspected they were.
Bottom half of radiator is cold or cool, and only top is hot.

I may experiment with adding some wavy metal to the back of the radiators and see if they cool down (and so radiate) at a faster pace.

Solarchaser

3rd post in a row, talk about talking to yourself 🙄😁

I've done nothing about adding a separate feed to the tank to take the pressure off the 50a mcb.
As Nick said earlier in the thread, octopus go at 12p for 4 hours has pretty much been replaced by intelligent which is 10p for 6 hours and at 6 hours,  3 x 3kw elements equates to 54kwh, which is plenty, and more than the 36kwh I get now.
It also runs 11:30 - 05:30 and so finishing as late in the morning will lead to less Heat loss before consumption as Ken had mentioned earlier in the thread also.
I will in all likelihood move to this in a months time.
It would cost £100 extra to do it just now, so I'll wait the month on my 4.5p rate running at 23.6kw which is about 96a on my 245v supply.
I'm doing this as I now need to charge the car as well as batteries and tanks... its a balance.

I have a fan on the wiring, as its a wee bit toasty 😮

70sbudgie

This is interesting. This whole post has made me think more about the details of heating design.

Btw, I'm guessing you don't mean airflow, as the fluid in your heating system is water. (Fluid flow laws still apply, so it is just semantics!)

Is it possible that the answer is just more simple than fins and laminar flow? When the pump stops moving hot water around, the heat in the water rises to the top of the radiator? Have you checked the tops and bottom of all your radiators? They may all exhibit the same behaviour.

The bit where the laminar flow might contribute, is that the ribs make the radiators more efficient at "getting rid" of their heat to the surrounding air. Without ribs, the flat panel radiators take longer to do this and therefore cool down more slowly when the pump stops. I wonder if they are also slower to feel warm than the ribbed radiators?

It then comes back to the question of whether we need to go back to the old style, ribbed radiators to optimise the efficiency of our heating systems? (I am now looking at all my radiators differently!) 

Solarchaser

I mean airflow over the radiators. 
Them warming draws the cold air, which is heated as it passes through rising up and heating the room.

The ch cut off 25 mins ago on the thermostat, and the traditional radiators are all cold at the bottom and middle, and slightly warm at the top.
The flat panels radiators are cold at the inlet/outlet pipes, cold at the bottom panel, warm in the next panel and proper hot on the other 5.
The ch supply from the tanks is at 34c and 30c.

Yeah thats exactly what I'm suggesting,  because the flat panel rads have no fins, they are great at holding onto heat.... but not so great at radiating it.

They warm up quicker than traditional radiators,  though that could just as easily be size related, as the flat panels will surely hold alot less water, and so will be quicker to expell their colder water as there is less to mix with the hot.

Reed_Richards

Solarchaser said:

I have 3 of the more "modern" or "stylish" type like this:-

I have a radiator that looks very similar (two actually, the other one is horizontal).  They were made/branded by Grant and are made of aluminium rather than steel.  They are said to use a smaller volume of water internally and therefore be faster to respond than a conventional steel radiator.  That seems to be the opposite of your retained heat experience.  My set-back kicks in at 22:30 which effectively turns the heating off so if I am up late enough I will get on a step stool and give the top of my radiator a feel.  

Heedtheadvice

"

3rd post in a row, talk about talking to yourself 🙄😁 "

....but are you listening to yourself ? :-:smile:

A bit toasty? Perhaps wiring still needs a bit more beef ?

Great to see you thinking through all the issues and sharing them. Keep up the good work.

Consider it would be good if you turned your heating off and all the rads stayed hot........ :-) .......I'll get my coat....

70sbudgie

Solarchaser said:

I mean airflow over the radiators. 
Them warming draws the cold air, which is heated as it passes through rising up and heating the room.

The ch cut off 25 mins ago on the thermostat, and the traditional radiators are all cold at the bottom and middle, and slightly warm at the top.
The flat panels radiators are cold at the inlet/outlet pipes, cold at the bottom panel, warm in the next panel and proper hot on the other 5.
The ch supply from the tanks is at 34c and 30c.

Yeah thats exactly what I'm suggesting,  because the flat panel rads have no fins, they are great at holding onto heat.... but not so great at radiating it.

They warm up quicker than traditional radiators,  though that could just as easily be size related, as the flat panels will surely hold alot less water, and so will be quicker to expell their colder water as there is less to mix with the hot.

Ahh, I think we got our wires crossed ( ) when talking about laminar flow! 

So you were talking about the airflow outside the radiator, I was talking about water flow inside the radiator. Both will contribute to the efficiency of the radiator. So I think that the fins disrupt the flow of air outside the radiator, increasing the movement of heat away from the radiator. I think the ribs do a similar job for the water, inside the radiator. There will always be a temperature gradient between the water in the centre of the hot water (pipe) and the water at the edge of the pipe / radiator. The ribs cause turbulence in the water flow which results in the heat being more evenly distributed (across the cross section of the pipe /radiator). Much like the destratification pump in your tanks.

So the water in the radiators without ribs, will hold heat better in the same way that your tanks hold heat better when the destrat pump is off. 

The airflow across the radiators won't be affected by the pump turning off, but the lack of fins on the same radiators will have a similar effect to the lack of ribs inside. 

Apologies if this sounds like I'm trying to teach you to suck eggs. It is more about talking myself through it to sense check as this is right at the edge of my understanding. 

So a more efficient radiator will cool down quicker, because it is better at getting the heat out of the water and into the air, not just adjacent to it, but in the whole volume of space it is heating.

Solarchaser

70sbudgie said:

Solarchaser said:

I mean airflow over the radiators. 
Them warming draws the cold air, which is heated as it passes through rising up and heating the room.

The ch cut off 25 mins ago on the thermostat, and the traditional radiators are all cold at the bottom and middle, and slightly warm at the top.
The flat panels radiators are cold at the inlet/outlet pipes, cold at the bottom panel, warm in the next panel and proper hot on the other 5.
The ch supply from the tanks is at 34c and 30c.

Yeah thats exactly what I'm suggesting,  because the flat panel rads have no fins, they are great at holding onto heat.... but not so great at radiating it.

They warm up quicker than traditional radiators,  though that could just as easily be size related, as the flat panels will surely hold alot less water, and so will be quicker to expell their colder water as there is less to mix with the hot.

Ahh, I think we got our wires crossed ( ) when talking about laminar flow! 

So you were talking about the airflow outside the radiator, I was talking about water flow inside the radiator. Both will contribute to the efficiency of the radiator. So I think that the fins disrupt the flow of air outside the radiator, increasing the movement of heat away from the radiator. I think the ribs do a similar job for the water, inside the radiator. There will always be a temperature gradient between the water in the centre of the hot water (pipe) and the water at the edge of the pipe / radiator. The ribs cause turbulence in the water flow which results in the heat being more evenly distributed (across the cross section of the pipe /radiator). Much like the destratification pump in your tanks.

So the water in the radiators without ribs, will hold heat better in the same way that your tanks hold heat better when the destrat pump is off. 

The airflow across the radiators won't be affected by the pump turning off, but the lack of fins on the same radiators will have a similar effect to the lack of ribs inside. 

Apologies if this sounds like I'm trying to teach you to suck eggs. It is more about talking myself through it to sense check as this is right at the edge of my understanding. 

So a more efficient radiator will cool down quicker, because it is better at getting the heat out of the water and into the air, not just adjacent to it, but in the whole volume of space it is heating.

I take it when you post you are doing the same as I am, talking it through to make sure it makes sense.
And for what it's worth I agree, that's what I've been thinking.

Reed, mine are definitely steel rather than aluminium,  and they definitely do heat up faster, but I just dont think they are radiating that heat away.
Interested to hear how you get on tonight.

HTA, ooft, listen to myself, no chance, who would listen to that idiot 😁

I'm a bit disappointed in the wiring from smart meter getting up to 62C, this was all new wiring put in less than a year ago when I was unlooped from the neighbour, specifically the old wiring was noted as being undersized tails, so... hmm!

Anyway 1 month only at this usage and then there will be far less current going through the smart meter as I'll be able to heat and charge over 6 hours instead of 4, and so all the current draw will decrease as the draw will be more spread out.

Until then it will be the fan on for the 3 hours as well.
I was hoping it would help with heating... bit surprisingly not 🤪

Reed_Richards

Solarchaser said:

Reed, mine are definitely steel rather than aluminium,  and they definitely do heat up faster, but I just dont think they are radiating that heat away.
Interested to hear how you get on tonight.

About an hour after the heating went off I remembered what I was supposed to do and tried the top of the vertical radiator that resembles yours and a tall vertical towel rail in the bathroom.  Neither were warm to the touch, nor cold.  However the water in my radiators never exceeds 50 C when they are on.