Horstmann Economy 7 Not Producing Enough Hot Water

[tomouse]

I have just moved into a new flat (newish build of 8 years) which has an electric storage heater (Horstmann economy 7, 170 litres). I keep it on a timer to heat the water for 5 hours each night. However, I find that it only allows for about 10 minutes of hot/warm shower water before it runs cold. This is not just true to the shower, but all of my water.

I called a plumber to have a look and he told me that the lower element (which he suspected might be the problem) was actually working fine. He also confirmed that the thermostat was set correctly at 60c. He was in and out within 10 minutes and concluded that I was probably using the system incorrectly.

I'm very familiar with the storage heater's manual and I can't see where I am going wrong. As far as I can tell, it's all very straight forward. I'm 99% sure it is all set up correctly.

Can anyone suggest any ideas that might be the problem?

 

[ProDave]

Have you got one or two immersion heaters (it can be configured for either)?

You are leaving the heater switch on "timed" aren't you?

Is the water coming out of a hot tap piping hot? i.e too hot to hold your hand under?

You probably need an electrician not a plumber to fix this one.

 

[tomouse]

Thanks for the quick response.

Yes, I keep it on 'timed.' And the water comes out piping hot while it lasts.

I'm afraid I'm not sure whether it's one or two immersion heaters. Any obvious way I could find out?

 

[ProDave]

Look at the cylinder. If you are not sure take a picture and post it here.

Also, try heating the tank with the two hour boost. Give it a few goes at a boost and see how much hot water you get then.

 

[steptoe]

Possible that the boost and E7 are crossed.?

 

[ProDave]

That's what I was thinking, hence asking if the boost gives a full tank (it's sounding like the overnight is only heating the top of the tank)

As I say, an electrician can test it for you to see what heater is getting power and when, which your average plumber won't be able to do.

 

[Andy™]

great logic there, 'i have an electrical problem, best call a plumber'

id go with either a fault element, or they have been wired wrong so only top element is on instead of lower

 

[tomouse]

Thanks for all your ideas. I'll try the boost for a couple of hours + post a pic.

 

[tomouse]

I turned off the overnight timer to test the boost. I kept the boost on for 3 hours and it supplied approx 12 mins of shower water at 35c (thermostat is set at 60c). I really don't know if that's normal with this sort of storage heater? Probably time to call in an electricial unless anyone has any other theories?

Link to my hot water tank photo - http://s204.photobucket.com/user/tomouse_bucket/media/IMAG1165.jpg.html?sort=3&o=0

 

[ProDave]

That tank has two heaters (see the two cables emerging)

It's normal for the boost to just operate the top heater to give you a quick top up, and that will only ever give you a half tank of hot water.

the overnight off peak should heat the bottom heater and give you a full tank of hot water.

It sounds to me like your Horstman might be configured wrongly so it's only ever using the top heater even for the overnight charge.  Get an electrician in to check it out.

 

[tomouse]

Cheers for that. Your answer makes a lot of sense. That could well be the problem. I'll get an electrician to look it over.

Thanks again for your help/input!