ECOBuild: Zypho Shower Heat Recovery

26 03 2012

We’ve been planning to use a drainwater heat recovery system for the upstairs showers. We intend to use a product from Itho, the SHRU60, connected to all of the upstairs shower drains to recover around 60% of the waste heat and feed it back into the cold side of the shower mixers. It has full SAP-Q and WRAS approval, so it is fine to use in the UK.

However, it has some disadvantages. Firstly it is a long fitting that needs to be installed vertically, meaning that it is no good for a ground floor shower (they do a spiral flat system for fitting under a shower tray but they are less efficient and very expensive). Secondly, it’s not exactly cheap at around £500 per unit (plus VAT). Itho were also conspicuous by their absence from ECOBuild. Last year they had a relatively large stand including their MVHR units, but nothing at all this year.

At ECOBuild a new system was on display from a small Portuguese company called Zypho. The Zypho 750 unit is designed to fit under a shower tray and is made from a tough plastic body with a copper pipe as the heat exchanger. The unit includes the shower waste along with a removable filter and is intended to have a waste trap on the other side of the exchanger. So far so good, in that the unit is suitable for use on a ground floor shower.

Zypho 750 Shower Water Heat Exchanger

Zypho 750 Shower Water Heat Exchanger

The incoming cold supply connects to a brass fitting on the side of the unit body and a similar boss provides a connection to the cold side of the mixer tap on the shower. This sounds good, but brings the first problem. These screw connections will be buried under the shower tray, and being mains pressure water, if they ever leak it could take a very long time to find out about it, by which time considerable damage could be done.

The major drawback is actually in the heat exchanger itself. From the diagrams it looks like this takes an s-shaped path along the length of the unit, back to the start and then back to the outlet for a total of three passes. If this diagram is representative, and there isn’t any detail on their web site to indicate differently, then it means that it isn’t a counter flow exchanger (where the coldest incoming water meets the coldest shower water). Also the area available for heat exchange seems to be relatively low, although the waste water probably stays in the exchanger a reasonable amount of time due to it’s relatively large volume. Both the lack of a counter-flow exchanger and the limited exchanger surface area make me think that it is unlikely to be as efficient as the Itho unit. However, Zypho’s graphs of performance and recovery indicate a much better heat recovery ratio, perhaps as much as 75%, which I find hard to believe. Unfortunately, it’s not currently SAP-Q rated, so won’t yet help your SAP rating.

The exchanger also isn’t yet WRAS approved, which means that it can’t be legally used in the UK. I think getting approval may be tricky, since there doesn’t seem to be a double barrier between waste and potable water, but this probably needs to be clarified.

On the positive side, it is relatively cheap at just €300 (plus VAT), although my current plan is to share one Itho for all of the upstairs showers which would work out cheaper than one Zypho per shower. However, it should enable some shower heat recovery for our ground floor shower once it has the relevant approvals.

It’s good to see some competition in this area even if the Zypho isn’t yet a suitable product for the UK market. This could change if their recovery efficiency is better than I suspect and they can get SAP-Q and WRAS approval. Certainly one to watch.



One response

26 03 2012
EcoBuild: Waste Water / Drain Water / Shower, Heat Recovery | Silver Spray, Droskyn Point, Perranporth, Cornwall.

[…] write up on the Zypho unit at Ecobuild on the HardHouse blog by Mark. – looks good, but questions the heat exchanger and it isn’t yet fully UK […]

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