Solar tank installation concern

[Stewart downs]

Hi

We have a leak into the tundish valve on a solar tank installation .

After doing some research we suspect that the original installation is in correct .

The e\v appears to be piped into the balanced cold take off on the cold inlet valve assembly.

Please see photo

Can someone please confirm this is ok?

Many thanks
Stewart d

 

[Madrab]

Yup, you're right. That EV is as useful as a chocolate teapot at the moment, being before the check valve!!

Get in touch with the original installers ASAP if it's a newish install, how long has it been installed? Even if it's been a while there should be a case to go back to the original installers anyway as that's not been installed correctly. Alternatively contact a qualified un-vented professional to get it corrected ASAP. Whatever you do, do it as soon as you can.

 

[Stewart downs]

Rob

Many thanks for the confirmation

System installed 18 month ago as part of a solar panel system.

It's worked ok but for the leaking cold inlet prv and until last month when the temperature pressure relief valve failed.Which overflowed into the cupboard and downstairs and.

At least this explains why the tundish has been leaking!

Will contact the installer and see if they will resolve.

Many thanks
Stewart d

 

[Agile]

Wet solar systems should be serviced every year!

Tony

 

[Stewart downs]

Tony

Thanks for the advise

I was not aware of this until I started to look at how the system worked. I generally do not like not understanding how things work and carry our research until I at least have a basic understanding. In this case I made a poor decision and trusted the professional company?

The advise from the original installers was not that good.

The solar store is being used as a pre heat to a combi boiler feed by an I boost from the surplus electricity from the solar panels. I had mistakenly assumed that the tank would not get that hot.The problem only arose when we left the house for a protracted period.
I have requested our heating engineer to service the solar store when he services our boiler.

Thanks again for the advise
Regards
Stewart d

 

[Madrab]

Couple of things to think about -

• The TP Valve should not have overflowed, the outlet of the tundish should be adequately installed to cater for the flow from the TP Valve without backing up.
• 2 issues (leaky PRV and TP valve failure) after only 18 months
• An EV that isn't connected correctly, which may or may not have caused the previous issues
• and .... did someone fixed these issues without noticing the EV wasn't fitted correctly, it should have been one of the things to be checked if a TP relief valve had let go.

I'd maybe get a reputable independent in to give it a once over safety check, any un-vented should be yearly checked, solar or otherwise as they can be dangerous. Make doubly sure they have an un-vented (UHW) G3 qualification, it's not a given. Have you manged to check the benchmark, is it completed correctly and do you have a notified cert from the LABC/CPS?

 

[Agile]

It seems that you don't have a wet solar system.

But a solar PV coupled with an unvented cylinder said to be used just to preheat water to a combi.

Firstly most combi boiler makers don't agree with doing that.

Secondly, if the inlet water exceeds about 25 C then the boiler may not be able to properly control the output temperature. Furthermore between about 20 C to 45 C legionella bacteria multiply very rapidly.

Tony

 

[Stewart downs]

Hi
Tony\Rob

Thanks for the further advise

The solar store is currently turned off and all electrical connections have been isolated and is only feeding cold water to the combi boiler. The system will not be used again until it has been checked by a qualified heating engineer (thanks to you and this forum g3 qualified) and the omitted certificate to confirm that the system is safe has been completed. And more importantly I fully understand how the system works including the risk from possible legionella issues.
I am hoping that the original installers will resolve the above issues.
Although a keen DIYer I do not work in domestic heating boilers and employ a reputable heating firm to service my boiler. My only experience of unvented heating systems has been through my ownership of several canalboats.
The majority of canalboats have a sealed hot water tank called a Calorifier which is heated by the engine via a heat exchanger and in some cases a secondary 240v \gas\ deisel heater. The only safety device fitted to this system is the temperature pressure relief valve. In the twenty years or so of extensively using this heating system, I have only experienced one occasion when the TPV was activated. This was caused by the engine overheating due to a burst saddle tank pipe (radiator hose in a car).
I had wrongly assumed that I would be getting a domestic equivalent to the above system (which I had found to be very safe) and did not pay enough attention at the time when the system was installed.
I spent several months researching\looking for a reputable renewable energy company to install a solar PV system and a solar water system.This is not an easy task as thousands have gone out of business over the last 10 years or so.
Spending 10k of retirement pension lump sum to reduce monthly living expenses was quite daunting.
But
The solar pv system has been a very good investment and has been very well installed. I have enhanced the benefits still further by self installing a 12v off grid system to use during the hours of darkness. The only issue has been the solar store and my lack of research to check that the company was experienced enough to carry out solar water heating works.
Thanks again for your advise and thanks to the people that set up this website \ forum.
Stewart d

 

[Agile]

I have to say that I would not call your cylinder a solar cylinder.

That term is normally used to describe a cylinder heated by a wet solar thermal system where tubes on the roof produce heated water which is then used to heat the domestic hot water in a solar cylinder.

That system is very efficient as it converts over 80% of the incident heat into usable hot water.

In contrast PV panels only convert up to 20% of the incident heat into electricity.

I would call your cylinder an electrically heated unvented cylinder used to preheat inlet water into your combi.

Because of combi temperature control limitations and the risk of legionella that is not very often used.

The immersion heater in your cylinder should have both a temperature control thermostat and a separate manually resettable overheat cutout. For the T&P valve to discharge due to temperature, both of those devices are either not present, not properly connected or unexpectedly both failed at the same time ! The latter is most unlikely.

So the expectation is that the cylinder is potentially unsafe.

Since the problems probably result from an incorrect installation, I would also think an independent engineer would be preferable.

Tony