Shower size, 6 kW really? Seems a good shower.

[Johntheo5]

The simple mains fed shower works quite well if the dynamic pressure is 2.0bar or greater as its flow control valve will then maintain a reasonable florate, I have a 9.0kw Triton T80Z upstairs with 2.5bar dynamic pressure downstairs and only have to adjust the temperature control a few times as the mains temp changes seasonally. If the dynamic pressure is 1.5bar ish, then a CWSC fed T80SR with its own integral pump is the better choice by far.

 

[Harry Bloomfield]

Your spec shows 3 heating elements and a motorized flow control valve as well as the solenoid valve so the flow rate is controlled automatically to give the set showering temp, the shower comes in two outputs, 9.5kw and 10.5kw I think.

I have never investigated it in that detail, I simply fitted it, and checked watched the wattage variation on the IHD.

 

[Harry Bloomfield]

The simple mains fed shower works quite well if the dynamic pressure is 2.0bar or greater as its flow control valve will then maintain a reasonable florate, I have a 9.0kw Triton T80Z upstairs with 2.5bar dynamic pressure downstairs and only have to adjust the temperature control a few times as the mains temp changes seasonally. If the dynamic pressure is 1.5bar ish, then a CWSC fed T80SR with its own integral pump is the better choice by far.

I measure 2bar, on the ground floor, the shower is in the bathroom, on the first floor.

 

[cdbe]

Interesting. But unless desperately poor why would you?

I have a big unvented but my showers have 8l restrictors - because I have teenagers and so am desperately poor (especially as they seem to have figured out that the rainfall heads aren't restricted). They'll be removed when I win the lottery or get rid of the teenagers.

My saving grace is that I have these fitted to each shower - the cold feed into the shower is actually warm.

 

[catlad]

My saving grace is that I have these fitted to each shower - the cold feed into the shower is actually warm.

I take it this is some kind of pre heating element?

 

[catlad]

If the dynamic pressure is 1.5bar ish, then a CWSC fed T80SR with its own integral pump is the better choice by far.

I think this might be the problem with my shower as other people in the house use the water to fill the kettle or dish washer or washing machine draws water it can't cope! So if I get a pump fitted this should help?

 

[Johntheo5]

There are various booster pumps around but not overly cheap, you are better off IMO to install a shower like the T80SR with its own pump but it has to be fed from a cold water storage cistern, no problems with hot/cold showers then.

 

[Why Not Indeed]

I take it this is some kind of pre heating element?

Looks like a "heat exchanger" that warms in the incoming water with the outgoing waste water.

 

[catlad]

There are various booster pumps around but not overly cheap, you are better off IMO to install a shower like the T80SR with its own pump but it has to be fed from a cold water storage cistern, no problems with hot/cold showers then.

Unfortunately I have combi boiler system so the T80SR is not an option.

 

[cdbe]

Looks like a "heat exchanger" that warms in the incoming water with the outgoing waste water.

Yes. As the hot shower water goes down the drain the heat is transferred to the cold water going up to the shower.

I think that I've got our 15kw heat only boiler to provide near combi style constant hot water to a shower.

 

[Ivor Windybottom]

I got confused as I read your post. When I got to the part about a hot shower cooling the floor tiles my brain exploded and I couldn't take any more.

Perhaps stick to actual physics?

 

[Ivor Windybottom]

I doubt you'd ever recover the installation and manucturing energy needed to install heat recovery from a drain. The waste from a shower isn't very warm, as it gets blown through the air, just like a cooling tower in fact.

 

[Madrab]

Is that just a pipe within a pipe, ergo the plastic cold mains pipe just runs up inside the PVC waste pipe or some kind of special PVC heat recovery/exchanger system that is purpose made? The shower water may warm up the incoming cold mains a little but surely it can't be very efficient, of course any heat gain is a bonus, so fair enough.

I think that I've got our 15kw heat only boiler to provide near combi style constant hot water to a shower.

Not sure how you managed that? The HO boiler doesn't interact with the cold or hot water system though, it only heats up the water in the cylinder so the boiler can't be directly providing any hot water unless the system is passing through a HEX?

 

[Why Not Indeed]

the plastic cold mains pipe just runs up inside the PVC waste pipe

You would surely use copper for this job.
No offence to @cdbe but it looks like a commercial product rather than something DIYed. Although it would be pretty straightforward to make.

Would be interesting to see the delta-T between in and out cold water on that thing.

 

[Harry Bloomfield]

I looked at making one of these, from copper, maybe a decade ago, I decided it was just not worth the effort + cost involved.

I considered it more likely to work, where a shower was over a bath, during the draining of the bath/after a bath, but then there would be little advantage to be gained, in prewarming the cold.