secondary return disagreement

[johntheplumb]

My boss is in the middle of doing a renovation in a busy restaurant. There will be new toilets installed on the ground floor with 3 Wash hand basins aprox 30 m from the ACV unvented hot water tank on the 1st floor. he's not a big fan of secondary returns reckons they're too inefficient. Our other options were a gas fired intantanious water heater which got shot down by the owner, or a 16Kw electric instantaneous water heater which sound a bit ridiculous when there is already a hot water supply in the building. Are sec returns as inefficient as he makes it out?? Would appreciate any facts and figures to back up my argument for fitting a secondary return.

 

[jase158]

secondary returns are inefficient I believe (pump running, extra water being heated) however they are more hygenic, water hotter so prevents bacteria in pipes especially when restaurant shut.

There is a slight water saving in the fact that you don't have to run so much water to get hot, but in a restuarant, I would be worried about water running out and would never fit a cylinder IMHO

 

[solutions]

They are inefficient if the pipework is inefficiently insulated. Should be insulated at least as well as the cylinder. But we both know how practical or likely that is.

 

[jase158]

Johntheplumb, why are you arguing with your boss?

 

[johntheplumb]

Well he's also my old man, we're more bickering than arguing

 

[AWheating]

50ltr unvented.

 

[Ermintrude]

Run a 10mm return back from under basins the losses on insulated pipework will be low. Don't use plastic. Put the pump on PIR sensor in loo. Comes on when they walk in and it's hot by time they wash hands Boosh!

 

[IDCHAPPY]

Run a 10mm return back from under basins the losses on insulated pipework will be low. Don't use plastic. Put the pump on PIR sensor in loo. Comes on when they walk in and it's hot by time they wash hands Boosh!

Sounds familiar, wasn't that the answer last time we got asked a similar question?

 

[kozak1968]

I wouldn't be worrying about efficiency with the amount of water being used. Just insulate the pipework as best you can. In a restaurant you wouldn't want to run out of hot water.

 

[johntheplumb]

I've seen this in older trends sounds like a good idea. It would work well in the quiter months but for the majority of the year a timer would be fine because of the large volume of people in the restaurant. Why no plastic? Resistance in the pipe or heat Loss??

 

[stevetheplumber]

I've seen this in older trends sounds like a good idea. It would work well in the quiter months but for the majority of the year a timer would be fine because of the large volume of people in the restaurant. Why no plastic? Resistance in the pipe or heat Loss??

you cant use plastic for secondary returns manufaturers dont allow it unless its changed

 

[stevetheplumber]

secondary returns are inefficient I believe (pump running, extra water being heated) however they are more hygenic, water hotter so prevents bacteria in pipes especially when restaurant shut.

There is a slight water saving in the fact that you don't have to run so much water to get hot, but in a restuarant, I would be worried about water running out and would never fit a cylinder IMHO

so what would you fit in a resturant jase?

 

[Marples]

Run a 10mm return back from under basins the losses on insulated pipework will be low. Don't use plastic. Put the pump on PIR sensor in loo. Comes on when they walk in and it's hot by time they wash hands Boosh!

I'd agree with ermin, especially with the sensor idea.
Who wants to stand there washing their hands in cold water, keep the customers happy.

 

[johntheplumb]

A bit late with the result but a 15ltr 4.5Kw Santon aqualine undersink water heater was fitted and it's doing the job fine so far