Electric Shower Heat Recovery Unit.

Yes - they are just a basic heat exchanger at about 60% efficient - you can demonstrate that from basic physics


They can recover heat from the waste - it's not that easy to get that heat anywhere useful, but putting it into the cold feed for an electric shower works OK (you get a slightly better flow rate) as does putting it into the cold feed to a mixer shower (you can use "warmer" cold to replace some of the "hot")


Given that showers are not particularly long affairs (unless you're a teenage girl) then their recovery potential is "low" and they would take a considerable amount of time to recoup the capital and installation cost and the carbon used in manufacture.


For those that are pretending to be "deep green" really  - better to spend the money on more wall or roof insulation or some draught proofing  - more effective return on the investment (in every sense)


Regards

The price seems totally unrealistic.


Also they don’t have an incorporated trap, so you need a running trap installed downstream, on most refurbishment jobs such an arrangement will be impossible to configure particularly if the tray is to go as flat as possible onto the floor.


Andy Betteridge

Given the price of that one, it will not pay back in the warranty period even if you shower petty much continually, at that  price I expect a heat pump, not a block of metal with some holes in at 1% of that cost you might be worth thinking about.

You  may do better running some  15mm copper inside 40mm waste pipe for a few feet and coming out at T pieces or tank connectors. I wonder how on earth you are supposed to clean it.

10 kW electric shower for 10 min = 1 67 kWh or about 25 p of electricity.


50% energy recovery = 12.5 p per shower.


So that's 8,000 showers for a price of £1k or one a day for 20-odd years.


The pipe in a pipe version is cheaper.


This sort of device may become compulsory in new builds. Much better to do away with baths altogether and just have showers.

The principle is good - although clearly better for showers than baths as for the latter the waste heat isn't available until after the hot water has been drawn off.


I gather that CAT had a play with various versions of the same idea quite a few years ago - but I understand it wasn't entirely successful (including one attempt at stored waste water to get around the 'bath' problem). One of the problems is that waste pipes inevitably accumulate nasty mix of grease, hair etc which can cut down the efficiency significantly - as Mike mentioned keeping such a device clean isn't going to be easy (unless someone's come up with a 'non stick' coating for the waste channel). I suspect that the cooling the waste water might also encourage the depositing and hardening of soapy/greasy/fatty deposits too.


Unless the technology has improved significantly, money is probably better spend on a decent low-flow shower head (some of the pulse type ones give a perfectly decent shower which much reduced hot water heating requirements).


  - Andy.

Not quite snake oil but more of a bootstrap idea by all acounts methinks. Good intention but limited return