Ditching gas, going electric immersion only, a wee project

Solarchaser

Hey, it's a glowing recommendation right?
The fact you have done it twice speaks to how well you think of them, so I'll definitely be looking at them 🙂

Solarchaser

The Eddi has finally arrived. 
Sound the trumpets 🎺 

No more playing with timers and hoping I guess right about the next day's solar.

Also with the eddi comes another CT clamp which I can finally use to let the myenergi system know there is a home battery too.

How nice is this? 


Turns out the lux inverters are a bit quicker to grab the excess solar than the eddi, but I've told the eddi it has priority over the batteries, so what happens over about a 30 second period is the sun comes out from the clouds and solar surges, the lux moves up to take it, and then the eddi grabs a bit and a bit and a bit more until it takes all the spare solar.

So here the solar had jumped up, and there was 1.1kw spare, lux tool it, then eddi stole it a bit at a time, so a few seconds after the screenshot, eddi was taking 1.1kw and battery was taking Zero
Day 1, but so far I'm delighted with the way its all working.

Heedtheadvice

I like it when a plan turns to happyness

Solarchaser

Another day, more flir pictures.
This is a tale of 2 one way valves, well 4 actually. 

And how not thinking about what you are doing can cause you to chase a fault that didn't exist😳

So first off the one way valves, as I said earlier I replaced the two single one way valves with two double one way valves between the tanks and the destrat pump, and this is the results 


The smaller cold tank on the left staying cold, as is the pump, and the right hand larger tank pushing its heat into along the pipes until the double one way valve, where it stops dead. 
Happy happy happy!

And so to the other set of double one way valves, I explained previously that I'd been stupid when fitting the central heating pump and filter return as I'd fitted them straight onto the tank encouraging thermosyphon to drag the heat all the way along the pipes in the downstairs in both directions. 

I fitted one double check valve after the pump and that seemed to stop it going any further, but the pump itself was always hot, hardly ideal.
So to resolve that I fitted two double one way valves at the exit of the tank coil, one pointing into the coil,  for the return, and one pointing out, for the supply.
Due to height restrictions I had decided to make a U loop on both sides, partially because I wanted both filter and pump to be mounted vertically and partially because I'd read that U loops were a good way to prevent thermosyphon. 
I have to say I am very surprised,  but also very glad to say the U loops work really well, and thats just as well, because the double check valves really don't work as well on the top of the tanks


The orange line is coming from the supply side of the coil, and although you can see the check valve is holding back a good portion of heat, there is still good transfer after the valve and onto the top of the loop... heat rises, as well as over to the right through my gate/ mixer valve  surprisingly,  but as it comes back down that whole pipe is cold to the touch, and so is the pump.
Similar story on the blue line which is the return to the coil, its not exactly hot above the one way valve as its a dead stop for anything going up the way, but its warm due to the transfer from the hot side, along the Tee from the gate valve.

So yeah, glad I added in the loops as otherwise I'd be somewhat miffed at having to drain the system (AGAIN!!!) to still deal with thermosyphon. 

After pressuring the system and running the pump I realised that all of the radiators were staying cool.
Eagle eyed readers may have already spotted the problem. 
I had fitted a 0.3bar restrictive double check valve on the inlet and outlet of my heat source, the coil, but nothing on the gate valve, so the easiest route for the circulating water was through the gate valve, ignoring the heating coil completely. 
So closed the gate valve bit by bit until the water in the coil was enticed to come out, and all working well.
Radiators are running a little hotter than I would like at the moment,  so fine adjustment on the gate valve required, but the finish line is definitely in sight 🤞

So to the fault that didn't exist.
There are 2 tanks, the 500l is the main tank, and is the one I've been heating, increasing it a few degrees at a time to see if I can get to around 92C consistently. 
I made the mistake of going as far as 95C and can confirm the 95C safety does open and does dump quite alot of rather hot water 🤦‍♂️

I've been trying to stop any hot water from the main tank leeching into the smaller tank, the two double one way valves at the top of this post were to stop flow between the tanks and onto the pump.
There are two other entrances to the tank, 1 at the other side where I've fitted a motorised valve, which I don't want to open until that tank is able to contribute heat to the main tank, and the last opening is the fill loop to top up the tanks, and where I have been monitoring the tank pressure.

The fault.
Since fitting the double one way valves instead of the singles, and refilling I can't seem to maintain pressure, overnight especially the pressure is dropping almost a bar of pressure.
Next day I top it up, and again it drops.

When draining the tanks for the valves, I also took the opportunity to add a second (ebay) expansion tank to the project.

So for the last week or more I've been fighting this pressure which I top up during the day, and then notice it falling at night.
Obviously I'm stripping everything off, I'm going over the compression joints, I'm going over the solder joints, I'm putting towels around everything to find where the leak is, but I can't find any semblance of a leak.
I isolate the expansion vessels believing they must have a broken membrane, but fault persist.

The only conclusion I can come to is that the tank has split internally,  and because its a tank in a tank, the internal tank is leaking into the insulation of the external tank, and only when that's totally full, will water leak out of the jacket.

Yesterday morning, guage had went to zero, so I once again topped it up to 1.5 bar, decided to isolate both expansion vessels and let it heat up with the Eddi all day, but on a whim decided to open the motorised valve and lock it open.

Came home to 5 bar in both cylinders (confirmed with another guage on the larger cylinder) and thought, right if there is a tear or hole in the cylinder I'll have blown it wide open and I'll see a puddle... but no puddle.

Long story short, I was reading the pressure in the small cylinder but heating the big one, and the addition of the valves to the smaller cylinder meant that the bigger cylinder couldnt add pressure to the smaller one when it had higher pressure (as it was heating) than the other during the day, but as it cooled and its pressure dropped, it would pull some of the water from the smaller cylinder through its one way valve, causing the pressure in the smaller cylinder to drop.

It's likely because of the 0.3bar needed to overcome the one way valve, filling the big tank from the small tank, that when I've refilled the tanks, I didn't completely fill them, and an air pocket was being expanded into.

To resolve this I didn't want to undo what I've done, so leaning on my new discovery of the U loop I've now linked both of the drain valves of the tanks together and opened the valves, so that the tank pressure can equalise through the lowest and coldest parts of the tank.
I will lose some thermal transfer here, but I think its the best solution for equalising the pressure in the tanks with the lowest heat loss.

70sbudgie

Solarchaser said:

The Eddi has finally arrived. 
Sound the trumpets 🎺 

No more playing with timers and hoping I guess right about the next day's solar.

Also with the eddi comes another CT clamp which I can finally use to let the myenergi system know there is a home battery too.

How nice is this? 


Turns out the lux inverters are a bit quicker to grab the excess solar than the eddi, but I've told the eddi it has priority over the batteries, so what happens over about a 30 second period is the sun comes out from the clouds and solar surges, the lux moves up to take it, and then the eddi grabs a bit and a bit and a bit more until it takes all the spare solar.

So here the solar had jumped up, and there was 1.1kw spare, lux tool it, then eddi stole it a bit at a time, so a few seconds after the screenshot, eddi was taking 1.1kw and battery was taking Zero
Day 1, but so far I'm delighted with the way its all working.

That's rather a pretty display. 😉

Coastalwatch

My SC, I have to admire your endeavours, perception and resolve I'm sure I'd have given long before arriving at any solution as you have. here so all credit to you and thanks for explaining it on here as well.

Solarchaser

Thanks CW, it's been a journey.

I mean if it all works as intended then in a years time I'll have forgotten how many times I've bumped and bruised myself, the fact I've redone almost every single pipe, and the frustration of thermosyphon 🤯😪 well I Hooe ill have forgotten. 

There's been a few times where I wish I hadn't started it, but then I think of the combi wheesing and huffing and that hot water dance of cold, hot, cold, warm, warmer, hot, and I'm happy.

I have to say also its in no small part down to you, when you got the thermal store a couple of years ago, to heat by solar and off peak, that's what set me on the journey, and until 5 months ago (yeah it really has been going on that long) I was planning on getting the same thermal store as yours, it came down to the fact I'd need 4 of them and the room to store them (plus weight of water at height).
So honestly,  thanks very much 👍
(and I don't mean for my two bruised knees and cuts in my back 🤣)

Coastalwatch

SC, you have my sincere apologies!

 

Freepost

I have found this to be a very interesting project and Solarchaser has mentioned a similar project by Coastalwatch may I ask for a link, to the discussions, I've tried to find it but not had much success.

Thanks

F.

Coastalwatch

Hi FP and welcome. I only came in part way through the discussions on "Hot water cylinder questions" on page three about halfway down. The link below will take you to p 3 but you will have access to the entire thread should it be of use. I picked it up from mmmmikey's input. We all learn from one another. I've found the G&E threads so helpful and am indebted to all the positive individuals who have contributed along the way.

Oh, the thermal store has continued to serve us well since.

https://forums.moneysavingexpert.com/discussion/comment/75586733#Comment_75586733