Unvented system gradual heat loss

[robbiejustice]

Hi all,

I have a Santon Premier Plus Imersion heater in a stanadard unvented system and have an issue...

My immersion heater comes on for a couple of hours in the early morning to provide us with hot waterfor the day. This has been working fine for years but recently I have found that the water is luke warm in the morning and almost cold by the evening whereas it used to be very hot in the morning and still quite warm in the evening.

When I use the boost then it is fine so I think the heat must be disspitating somehow. I have felt the pipes a number of times after a boost and the cold water feed is still cold and hot water outlet is luke warm. I have checked for a leak on the hot water taps/showerheads but have not found anything. Also, there is no discharge into the tundish from the RV and expansion valve.

Does anybody have any ideas/thoughts on what might be going on?

 

[dcawkwell]

The other more typical cause is the thermostat is going and not bring
up to the correct temperature in the first place.

Similarly the immersion heater could actually be going and therefore isn't giving the heat.

I would look to the thermostat first.

 

[robbiejustice]

Ok thanks. Can anyone replace a thermostat or can only a qualified electrician do it?

 

[dcawkwell]

Ok thanks. Can anyone replace a thermostat or can only a qualified electrician do it?

The government would have you believe that only a fully qualified
person surrounded by safety notices could do it.

In actual fact it is straightforward. You will need to order the part for your cylinder they aren't available over the counter.

If you have a multimeter you can measure the resistance of the thermostat and find out if it is the thermostat or the immersion that is your problem.