Divert excess PV energy to "heat" hot water cylinder

rolion · 04-01-2017 07:22PM

Hi,

My iBuddy works great, so far !
Heard that immerSUN is back in business ,anyone confirm it !?

quentingargan · 05-01-2017 08:59PM

rolion wrote: »

Hi,

My iBuddy works great, so far !
Heard that immerSUN is back in business ,anyone confirm it !?

Yes - back available again now. The company and its stock has been bought out of receivership

leo738 · 12-01-2017 09:00PM

I recently had 12 panels installed with a Solic unit. I frequently find that the thermostat on the immersion cuts out (at 60°) when the top half of the cylinder comes to temperature, with the bottom half fairly cold. I installed a 36" immersion (max possible) but not a huge improvement. I could set the thermostat to a higher temp & use a TRV or even change the tank but before doing that I thought I might install a small pump & non return valves (with associated logic etc) that would circulate the hot water from the top of the cylinder to the bottom. As soon as the thermostat closes the pump would shut off.

Any thoughts?

12-01-2017 09:36PM

Cascaded elements? Upper first, lower second.

rolion · 12-01-2017 11:12PM

leo738 wrote: »

I recently had 12 panels installed with a Solic unit. I frequently find that the thermostat on the immersion cuts out (at 60°) when the top half of the cylinder comes to temperature, with the bottom half fairly cold. I installed a 36" immersion (max possible) but not a huge improvement. I could set the thermostat to a higher temp & use a TRV or even change the tank but before doing that I thought I might install a small pump & non return valves (with associated logic etc) that would circulate the hot water from the top of the cylinder to the bottom. As soon as the thermostat closes the pump would shut off.

Any thoughts?

Hi,

Do you have this type of cylinder at the moment in your home !?

I advise to read in your own time about:
-solar cylinders with multiple coils,one for solar one for third party heater
-thermosyphon effect in a hot water cylinder
-hot water convection

Basically,once the water reaches a certain threshold ,THE heating element stops heating,be gas oiler,solar pump or electrical immersion.
Then the "thermosyphon effect" kicks in and heats the water from the top to the bottom.As the water outflows from top,you will have always with priority hot water at the highest temperature available .IF you dont use it,the cold water at the bottom gets warmed-up by the same effect.IF you will circulate forced tha water,you wil not have hot water for daily instant needs (off the top of the cylinder) but rather a more constant temperature that may not feel so friendly. My system is set to go maxim 40" due to economy and then stops. For summer,it may needs readusting.

NOW,my issue / complain is that the immersion element breaks this gravity effect and may create troubles .

My next month plan is to get a 150L smaller cylinder that has input from cold water tank/pump and output to the main solar 300L cylinder input,with only immersion connected to my iBoost.When excess of electricity available,that will heat the immersion in the 150l creating a more compact bubble and heating it faster.That water then gets transferred to the 300L cylinder and i hope it will maintain the status quo of the gravity/thermosyphon effects.

Below is a typical solar tubes installation.
You can replace the solar pump if you have a two coils cylinder.
Not sure why you will need that.

Below,is my solar tubes reading from some time ago.
Top,is the top cylinder readings, heat by the gas boiler from previous night.
At some point in the morning,you can see the top collector temperature raising,warming up the bottom of the cylinder but top stays the same.Then,consumption kicked in and affected the sensors !

quentingargan · 13-01-2017 12:37AM

leo738 wrote: »

I recently had 12 panels installed with a Solic unit. I frequently find that the thermostat on the immersion cuts out (at 60°) when the top half of the cylinder comes to temperature, with the bottom half fairly cold. I installed a 36" immersion (max possible) but not a huge improvement. I could set the thermostat to a higher temp & use a TRV or even change the tank but before doing that I thought I might install a small pump & non return valves (with associated logic etc) that would circulate the hot water from the top of the cylinder to the bottom. As soon as the thermostat closes the pump would shut off.

Any thoughts?

You could increase the stat, but not if you have hard water - it would cause excessive limescale. And yes, you would also need an anti-scald valve on the output, but it is kind-of recommended nowadays to have one anyhow.

I put a cycling pump on my cylinder for this reason once. I had no lower immersion slot. You just circulate water from the feed to the output. But it needs to be a stainless pump, not your normal cast iron central heating pump. And you would need to insulate everything. But that would work. If your cylinder is otherwise well insulated, it works well.

Another option would be to get an element made up that has more element material looped several times at the end, so that there is more heat produced lower in the cylinder. Also, a longer thermostat pocket used to be used in the past... There are companies in Ireland that make one-off elements.

leo738 · 13-01-2017 10:25PM

Thanks for the replies,

I have a standard tank & as there's only 3 in the house we don't have the need for a large cylinder. I'd rather not go to the expense of another tank etc so this is why I'm probably going to try the pump solution. (I'd like to stay away from TMV's due to the possible pressure drop). Just looking for the right pump, probably small (15mm) or so..

Regards,

Leo

leo738 · 14-01-2017 02:43PM

Actually looking at the cost of a pump, valves & fittings etc it would probably be just as expensive as a new tank with an immersion fitting located at the bottom of the tank. Do such tanks exist?

air · 14-01-2017 05:25PM

You could just stick a 230V heating pad to the bottom of the tank perhaps?

leo738 · 14-01-2017 07:54PM

air wrote: »

You could just stick a 230V heating pad to the bottom of the tank perhaps?

Interesting idea. The only snag is that the bottom of the tank is significantly concave I think. Are heat pads flexible?

leo738 · 19-01-2017 08:50PM

I looked into getting a custom immersion made up but doesn't seem like a runner. A new custom made tank doesn't seem too expensive, in the region of €250 to €300 so probably going down that route.

I'll probably get a slightly larger tank & put in two immersions, one mounted at the top & powered first and when it cuts out the second lower immersion will heat the lower half of the tank. It means that hot water should be available quickly but that if power is still available the entire tank should be heated.

I attach a crude picture.

quentingargan · 19-01-2017 10:21PM

leo738 wrote: »

I'll probably get a slightly larger tank & put in two immersions, one mounted at the top & powered first and when it cuts out the second lower immersion will heat the lower half of the tank.

Yes - that should work nicely.

rolion · 19-01-2017 11:01PM

@leo
Go for IT !!!

leo738 · 20-01-2017 02:53PM

afraid!

rolion wrote: »

@leo
Go for IT !!!

Dint have have the space I'm afraid!

leo738 · 14-02-2017 09:38PM

For anyone interested it was about €350 for a 42 x 18" tank. Working well so far.

dathi · 14-02-2017 09:49PM

leo738 wrote: »

For anyone interested it was about €350 for a 42 x 18" tank. Working well so far.

now all you need to do is insulate the pipes

M.T.D · 16-02-2017 03:06AM

Would mounting the immersion externally not make more sense in this situation, I think they are called willis. You can even get heating coils fitted in an external (to your tank) so that the top of the tank always heats first and if the "willis" is drawing from the bottom of the tank it will eventually heat the whole tank. With hot water at the top and cold at the bottom, much better than a tank full of uniformly warm, but not hot enough for a shower, water

quentingargan · 16-02-2017 11:39AM

M.T.D wrote: »

Would mounting the immersion externally not make more sense in this situation, I think they are called willis. You can even get heating coils fitted in an external (to your tank) so that the top of the tank always heats first and if the "willis" is drawing from the bottom of the tank it will eventually heat the whole tank. With hot water at the top and cold at the bottom, much better than a tank full of uniformly warm, but not hot enough for a shower, water

Yes, provided the system is well insulated. I found sometimes there was a lot of heat loss off the Willis heaters, but the system works OK.

CyberSecurity · 12-09-2017 01:47PM

Hi guys, has anyone got any recommendations on a good Solar pv diverter to buy.

I am currently looking at some of the following below:

Anyone have hands on experience installing or using these in a house environment?

PowerDiverter

https://youtu.be/5GnXm21ALZE

but I have seen other examples such as

Immersun ( Have gone bang!! as of 2017)

https://www.youtube.com/channel/UCosyQebcO5Q_x_ZBXdrJj3Q

https://www.youtube.com/watch?v=IKnB4S6-p5s

SolariBoost

https://www.youtube.com/watch?v=y2a9Z-L0i5k

Gumbo · 12-09-2017 01:55PM

CyberSecurity wrote: »

Hi guys, has anyone got any recommendations on a good Solar pv diverter to buy.

I am currently looking at some of the following below:

Anyone have hands on experience installing or using these in a house environment?

PowerDiverter

https://youtu.be/5GnXm21ALZE

but I have seen other examples such as

Immersun

https://www.youtube.com/channel/UCosyQebcO5Q_x_ZBXdrJj3Q

https://www.youtube.com/watch?v=IKnB4S6-p5s

SolariBoost

https://www.youtube.com/watch?v=y2a9Z-L0i5k

Many people complain about interference on the cheaper units. You should use a VariSine™ PWM technology based unit is what im led to believe from posts on this forum.

For that reason im using a Myenergie Eddi unit.

CyberSecurity · 12-09-2017 02:10PM

kceire wrote: »

Many people complain about interference on the cheaper units. You should use a VariSine™ PWM technology based unit is what im led to believe from posts on this forum.

For that reason im using a Myenergie Eddi unit.

Thanks very much for the fast response. I haven't seen this brand before. Will have a look now. Thanks again.

a148pro · 20-10-2017 08:59PM

leo738 wrote: »

For anyone interested it was about €350 for a 42 x 18" tank. Working well so far.

Leo was this a standard enough tank, I'm putting in a system and hope to allow for Solar PV. Would wreck my head if I was heating enough water for only one shower when I could heat more on the good days?

Does the tank have to have the double inlet, I assume you can't just screw it in afterwards :pac:

Gumbo · 21-10-2017 12:32AM

a148pro wrote: »

Leo was this a standard enough tank, I'm putting in a system and hope to allow for Solar PV. Would wreck my head if I was heating enough water for only one shower when I could heat more on the good days?

Does the tank have to have the double inlet, I assume you can't just screw it in afterwards :pac:

Looks to be a standard tank.
You could go with a stainless steel one but they are more expensive.
I put in a 54x18 cylinder and single immersion.

You just plumb it and pipe it as normal, standard immersion etc.
The divertor turns your immersion on so there’s no specialist plumbing or even wiring as the divertor is connected to the immersion feed in your fuse board.

flyandrain · 06-11-2017 12:54PM

anyone would recommend a company to provide and install immersun, it looks good system , Please PM.

Divert excess PV energy to "heat" hot water cylinder

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