Recircularion and Thermosyphon Systems

[solarCH]

Hi, does anyone have any experience recirculating water around a circuit with a Thermosyphon System?

The solar unit is quite far from the furthest tap (35m) and there is quote a lot of water run off to warm water.

Thanks

 

[solarCH]

bump.

 

[Dotty]

I'd say that was a no to be honest lol

Pm Ecowarm, he's pretty good

 

[Dotty]

Hang on...... I just reread that! You talking about a secondary return?

 

[solarCH]

Yes, recirculate the water in the secondary circuit. I guess we would need a pump valve that could also close the mains water feed into the deposit while it circulate the water in the tubes.

 

[ecowarm]

You're not explaining it very well, but if you look here page 3, or look at the instructions that came with the unvented cylinder.
If your cylinder has no secondary connection you connect in to the cold inlet with a swept tee and nrv.
It will be in the instructions, are you qualified to do this work?

 

[Dotty]

What are the qualifications yoou require to work on this over there in portugal?

 

[solarCH]

What are the qualifications yoou require to work on this over there in portugal?

Not sure about Portugal, in Spain you need to be certified and registered as an installer by the Ministerio de Industria.

 

[markfxy]

In spain all you need a bag of tools and an english reg estate car

 

[poorman]

When I asked about this I was told that the cost of running the pump (UK) would outweigh any savings. To get warm water in the morning in our bathroom we need to run off about 1 1/2 gallons of cold water plus nearly 1/4 a gallon in the kitchen this could amount to nearly 1000 gallons of water a year, this can happen twice a day.
So is putting a secondary circuit in stop this worth it?

 

[diamondgas]

When I asked about this I was told that the cost of running the pump (UK) would outweigh any savings. To get warm water in the morning in our bathroom we need to run off about 1 1/2 gallons of cold water plus nearly 1/4 a gallon in the kitchen this could amount to nearly 1000 gallons of water a year, this can happen twice a day.
So is putting a secondary circuit in stop this worth it?

Well insulated and installed correctly has to save you money as you're not wasting having to re-heat the gallon and a half of 'dead leg' before useful hot water is available IMHO. Just put a secondary circulation in my gaff and the results are that I have 60 degC water virtually instantly to all taps... ... I'm thinking about rigging up some kind of switch that'll turn the secondary pump off when not needed.

 

[SimonG]

Well insulated and installed correctly has to save you money as you're not wasting having to re-heat the gallon and a half of 'dead leg' before useful hot water is available IMHO. Just put a secondary circulation in my gaff and the results are that I have 60 degC water virtually instantly to all taps... ... I'm thinking about rigging up some kind of switch that'll turn the secondary pump off when not needed.

You want a pir sensor in the bathroom that detects movement and kicks in the pump and then runs on for a set period

 

[diamondgas]

You want a pir sensor in the bathroom that detects movement and kicks in the pump and then runs on for a set period

What if the missus is doing the dishes in the kitchen mate? lol ..... Minimum run to any hot tap is about 9m ... max for me is about 15/18m... I've considered some kind of time delay attached to the cylinder stat that'll shut off once temp is reached but kicks into action, via a flow switch on the cylinder cold feed? Got to get my head around the technical side of that or just change the times to suite 'her indoors' needs ? :lol:

 

[Nostrum]

Chris Watkins mentioned some new pumps which I think could be timed, or thermostatically controlled. Might be worth asking him.

 

[Roger Welton]

When I asked about this I was told that the cost of running the pump (UK) would outweigh any savings. To get warm water in the morning in our bathroom we need to run off about 1 1/2 gallons of cold water plus nearly 1/4 a gallon in the kitchen this could amount to nearly 1000 gallons of water a year, this can happen twice a day.
So is putting a secondary circuit in stop this worth it?

What you want is one of these, modulates pump speed down when return temp comes up.

edit to add link!!

Grundfos Comfort | Grundfos

 

[Pipes Plumbing]

Or you can do it with a pipe stat (on the return run a good distance after the last draw off) and a timer if you want to do it on the cheap...
Wire the timer through T1 & C on the stat to the pump. Set the stat at 55-60c so that once the pipe temp is up, the stat breaks on rise and stops the pump.
The timer allows you to set on off periods so the pump only activates during periods of expected demand... i.e Off overnight and during the day if everyones out at work, but on mornings and evenings when people will be using the hot stuff.

 

[peteheat]

Some solar controllers have an option to activate a pump on the secondary return every 15 minutes to allow the water drawn at any tap to be hot all the time.

There is more to consider than just the cost of running the pump, many water suppliers are now using metered systems to charge for all water used, so less waste is better on the bill and of course the environment.