ElectraStream Boiler - wet electric central heating

[SarahThomas]

Hi,

I am looking for some advice on how to make the best use of wet electric central heating provided by an ElectraStream boiler. We're moving from gas central in our old flat to this system in our new one. We have been told by our new landlady that we need to setup an Economy 10 tariff. As we are out at work between 8am and c.5pm and wouldn't expect to want heating in the middle of the night (i.e. between 1am and 4am), we don't understand how we'd benefit from the Economy 10 tariff. Does the ElectraStream boiler have the capacity to heat up water during the cheaper periods, store the hot water and then distribute it in the radiators at the times we'd actually want the heating (i.e. between 6-7am and 6pm to 9pm)?
Any advice on how to use this boiler system properly would be much appreciated.

Thanks,

Sarah

 

[BLOD]

The Electrastream is an unvented hot water cylinder that supplies hot water to your taps, shower etc.
It's also used as a heat store to heat the water via an internal coil thats pumped round the radiators.

Economy 10 will keep it hot all the time so you can have hot water or heating whenever you might want it.

There's info on it here,
http://www.gah.co.uk/downloads/GAH-Electrastream-user-guide-installation-instructions.pdf

 

[Blackie78]

Hi I've read the manual and am still a bit lost with this system, if I set the time in line with my Eco 20/20 tariff (IE 9pm - 7am) then the heating is on all night but not during the day when I want it. How do I set it to store hot water for when I need it say at tea time when we get in from work, I don't want heating on while I'm in bed. All I can see in the manual is that turning the heating on during peak times will cost more. Help appreciated.

 

[doitmyself]

The hot water that comes out of the taps is not the same as the water which circulates through the radiators; look at Fig 1-1a.
The tap water occupies the large space in the cylinder; the rad water is in the coil. Heating up the cylinder overnight will give a large volume of very hot water. As well as feeding the taps, via a valve which mixes cold with hot so the tap water is safe, the water in the cylinder can also heat up the water in the coil; and so heat the rads. However this will only happen if the pump is working.

The pump is controlled from the Electrastream control unit. However this only controls the times when heating is available, you also need a thermostat so the heating only comes on if the house is below temperature. This is shown in fig 2-1a, which also shows a motorized valve, the purpose of this is to ensure water only circulates through the rad when it is needed. Fig 3-3a shows how the motorized valve should be wired.

Unfortunately the Electrastream controller assumes you want the heating on at the same time as the hot water, which is OK during the day but not at night. You can turn the heating off over night by pressing the down arrow during an auto on period, but you have to reset it each morning - see para 2-3.5. A Programmable room stat overcomes this.

 

[Blackie78]

Thank you so much, I get it now, a programmable room stat will enable me to set it so it will no be asking for heat during the night, then in the morning loads of cheap hot water for the taps that will also heat the water for the rads when I need them. I'll use the wife as a programmable room stat for now, she's good like that.

Just one other question then, which I will try to monitor over the next few days anyway, but how long should it take to heat the water in the tank over night to get to the target temp, I have this set at 65. Also when it hits 65 does it just keeps it at that temp until the control panel turns it off and once it does how long will he water stay hot for?

 

[Blackie78]

Thanks for this I understand now. How long should it take to heat a tank over night and when the timer goes off how long will the water stay hot for? Cheers

 

[garnhamr]

don't want to take away the point of this thread but how effective are these systems?
do you have to be really carefull with how much hot water you use?
say you heat the water via economy only and then have a bath in the morning, would you then have not enough heat for heating?

ah ok just googled economy 10. surprised i've not come across this system b4 tbh seems good.

 

[doitmyself]

How long should it take to heat a tank over night and when the timer goes off how long will the water stay hot for? Cheers

According to the manufacturer's literature it will take 50 minutes or 58 minutes (depending on which size cylinder you have) to raise the water temperature by 50C.

The literature also says that the heat loss is 1.7 or 1.9kWh at 60C. I don't know what this means as a temperature drop, but it complies with current Building Regs requirements.

Obviously, when you use hot water for washing etc, it gets replaced by cold water, which will need reheating. When the central heating is on, the water in the cylinder will also cool down as heat is transferred to the CH coil.

You say that you have the water temperature at 65C. It might be worth raising this to 70C as the thermostatic mixer will ensure that the water coming out of the tap is still at a safe temperature, but there will be less hot water in the mix. The house will also heat up faster if the water is hotter.

When the timer says the cylinder is being heated, the cylinder thermostat will keep the water at the set temperature, depending on how low the temperature drops before the thermostat closes. For example the stat may open at 70C and close at 60C. It certainly won't be like a room stat which has a 0.5C to 1C difference between on and off.

 

[commgas]

These GAH units have 3 immersion heaters and the controller decides how many of the heaters need to be on according to the water temperature, they work in 2 degree C steps e.g. if the set point is 60 deg.C then at 54 all three will be on, at 56 two will be on, at 58 only one is on and at 60 none will be on.
The controller does allow for time control of the heating but certainly a programmable room thermostat is much better, there is a known fault with the failure of the PCB, contact me for further advice on that.

 

[Unregistered]

hi i think I'm experiencing a pcb issue. only heat 1 working what is your advice? thanks in advance

 

[Rickster123]

Please register and start a new thread. Thanks.