Instant water heater problem

[flyingsparks]

customer of mine has a 12kw instant heat water heater in a small cabin for kitchen sink and shower. It needs a flow of at least 3l/min to turn on. We have set the stop cock to get this flow rate and it turns on ok and gives adequate water of around 40oC. Trouble is if it's left over night etc it needs the stop cock turning up a bit to more like 5l/min to get it to operate and then you can turn it down again to 3l/min. Trouble is at 5l it's not hot enough.
Any better ways to control the flow and make sure it operates every time?
This is in a holiday let they rent out so it needs to work every time.

 

[Dan Robinson]

And the heater us a........?

 

[FiremanT]

Has the appliance not got a control tap, or does it run through the hot water tap? Either way, you would normally have the SC open full and control flow with tap

 

[flyingsparks]

No the only control at present is the stop cock. The heater is a flowmaster I think?!

 

[wv62]

So every time you want water you have to go out and turn the stop cock on and off? If it's for hot water and a shower that would mean both the kitchen sink and shower come on as soon as the stop cock is turned on? Sureley the shower and sink have separate controls and you would regulate the temp of the water by adjusting the flow on either the shower control or the sink tap.

 

[Phill Peck]

U fit 3l/min limiters to the outlets.
If the unit is specified for 3l/min and the flow switch doesn't start the heater it is faulty.

 

[flyingsparks]

U fit 3l/min limiters to the outlets.
If the unit is specified for 3l/min and the flow switch doesn't start the heater it is faulty.

The flow switch was replaced in case it was faulty but it's the same. Can you link to these 3l/min limiters? At present obviously there is kitchen and shower taps, but to limit the flow of water down to 3l/min the SC is turned back. So with these limiters, could you leave the SC on full, and that would give enough flow/pressure(?) each time to operate the heater?

 

[Phill Peck]

Flow rate would stay the same though in theory.
These go in the end of taps just google flow limiters.
http://www.bristan.com/taps/flow-limiters

 

[flyingsparks]

OK thanks Phill. I will have a look into this.