Tankless Electric Water Heater Installed on the Outlet of a Hot Water Cylinder?

[salzar]

I s it possible to install a tankless water heater on the outlet of a hot water cylinder feeding a thermostatic mixer shower? the tankless heater would need to be thermostatically controlled and capable of operating at low pressure. The advantage would be that the majority of the time the water wouldn't need heated due to the cylinder being hot from the oil fired boiler, but when this ran low the tankless heater would automatically top-up the water temperature. I know an Immersion heater is simple and cheaper, but as this setup would be automatic, some people might prefer it. Does such a tankless heater exist, has anyone done this before? This would be in place of the current installation which has a hot water cylinder, but the hot water is never used because the shower is simply an electric shower. Thanks

 

[ecowarm]

welcome to the forum, sound a strange idea to me, why not just leave the electric shower in and also have a thermostatic one?

 

[salzar]

My Gran's bathroom is being re-fitted and I was hoping for an improvement in terms of running cost, but don't think the choice of two showers would suit her.

 

[ecowarm]

Stick with the electric one then, cost of oil is much the same as electric anyway imo

 

[salzar]

Seeing the hot water is there anyway, at a cost of about 6p a unit whereas her electic is now 17p a unit (Northern Ireland little choice of supplier). This is why I was making this odd suggestion about plumbing it.

 

[ecowarm]

yes but how long are you in the shower for?

 

[salzar]

1/4 hr @8Kw is 2Kwhr 34p
If electric shower every other day 182 days @ 34p a day is about £62 per person per year. As the central heating is producing hot water anyway and more efficiently than coming from a power station it would be better for the environment too.

 

[Mike Jackson]

Have you taken into account the standing heat losses from the cylinder in your calculations? Just turn the hot water off and heat what is needed. Possible fit a small electric heater for the kitchen sink. no point in heating a full cylinder of water for a small amount.