Indirect Hot water tank failure

[Tristar]

Hi guys, I have a 12 year old indirect 120L HW tank, 1040mm x 400mm, that has failed internally such that the CH water is leaking into the hot water supply. Is this sort of failure common? Secondly, are all the pipe connections of similar size tanks in the same place? Also what is the largest immersion I can fit in such a tank? as I utilise solar electricity to heat when I can.

TIA

 

[flameport]

1 - not particularly common, but certainly can happen.

2 - depends on make/model, plenty are in similar places but not necessarily identical.

3 - 3kW for a standard immersion. Others exist for a lot more money, but no real point. Even from totally cold, a 3kW immersion will heat the 120 litres of water to 65C in less than 3 hours. Higher power would reduce that time, but only if you actually have more than 3kW of solar power available. Heating of hot water is a tiny percentage of fuel use anyway, the savings to be had from electric solar hot water heating are generally insignificant.

 

[Tristar]

Thanks very much, very useful. Regarding solar, as we use more electricity in the evening, most of my 4Kw array feeds back into the grid during the day. I am paid just under 4p per Kw for a 'deemed' figure of 50% of generated solar to the grid, but my leccy friend who fitted them, and his own, and has fitted a meter to check, tells me that his feedback figure is about 75%, so I might as well use it to heat my water.

Thanks again.

 

[Tristar]

I forgot to ask, as there is a wide variation in prices for these, is it a case of, you get what you pay for, or will one from the well known DIY store do just as well?

 

[MeldrewsMate]

...the savings to be had from electric solar hot water heating are generally insignificant.

I disagree, I get almost all my hot water from my 4kWp solar PV array between March and November.

OP, the use of a solar power diverter such as Solar iBoost or Immersun will mean you ONLY use the excess solar power to heat the water, as it's quite rare for the 4kW (not Kw!) array to produce more than the 3kW required for the immersion heater. These diverters solve that problem by modulating the power used down to that generated on the roof.
Remember, every kWh you 'export' earns you about 4p, but it costs you over 4 times that to re-import it.

MM

 

[Tristar]

Thanks, I've had a Solar iBoost since they became available, and yes, I am well aware of the financials.