unvented secondary return

[mike_s]

Can the pump be connected to a flow switch? I thought I seen this somewhere, I've got a customer who has one of these systems and finds it annoying how everyone has to synchonrize their showers unless the pump is on all day and evening so I thought a flow switch would be obvious as the pump is only required once the hot taps are turned on preventing the long wait for hot water?

I've just been re-capping about secondary return circulation in 2 unvented text books but no mention of a possibly flow switch. will speak to manufacturers tomorrow about a possible solution.

 

[mikegas]

you need the pump to be flowing prior to opening the tap in order to get instant hot water

 

[SimonG]

Thought at first it was a good idea, but I'm not too sure the more I think about it. It will only operate the pump on opening and shut off again when tap closed, could have a pump over run on it, but still means first draw off has to wait. Prefer a timer on the pump to operate at peak times.
Might need some more thought.

 

[tweakyboy]

Or why dont you wire it to a PIR? So it comes on when you walk in the bathroom etc?

 

[ecowarm]

It would turn on when tap opened and then stay on! you need a timer

 

[SafeGasInstall]

PIR ???? groundfoss do the combi pump wich has timer and temp sensor

 

[SafeGasInstall]

Grundfos UP15-14BXUT Secondary Circulator with Timer and Thermostat

 

[mike_s]

What is a PIR? Ecowarm why would the pump stay on once the tap was turned off?
Probably not the best idea after reading your thoughts, just thought there would be a better alternative to it being timed. I know it wouldn't be as quick on a flow switch but may still be an improvement I thought.

The cylinder and secondary circulation pump timeswitch are in the loft, maybe they would find this switch more convenient in the bathroom. I never installed the system.

 

[SafeGasInstall]

it need to stay on so it deliver hot water ready to be drawn off from the taps when ever is going to be the next time ,eliminating waiting time and kill the dead leg ,plus if it has temp sensor it will maintain correct temp in the pipe work ,so if it cool down over night you dont have to wait 2min for the worm water to be delivered ,my personal understanding of the hot water pump

 

[tweakyboy]

It would turn on when tap opened and then stay on! you need a timer

Yeah it does work, we have done it before. Put it near the door to bathroom/kitchen etc, then have it on a 20min/30min run over then it shuts off. It works a treat and only comes on when someone enters the room.

 

[tweakyboy]

What is a PIR?

Passive Infa Red senor, you know you get them on outside security lights. They come on when you walk near them, also the same for alarm systems.

 

[SafeGasInstall]

but then will it maintain the correct temp in the pipe work ,so when you get in the morning and open the hot water tap
will it be there any hot water .....or you have to wait in the shower to get the water which to me it will make it less useful in this scenario .pls correct me if i am wrong !

 

[Kev the gas]

A secondary pump is used to reduce the lag time for receiving hot water to long distance pipe runs.

Why not wire in an old fashioned Immersion heater timer ?, set the pump to run for a short blast of 15 mins and then off.

Set this to happen during the day and off @ night.

If the water is cold when demanded then there is a problem with the insulation of the hot water pipes and the secondary return.

Kev.

 

[SafeGasInstall]

you mean put the pump in the bathroom or put sensor there ? as if pump is in bathroom and there is more then one dead leg and the other shower is 10-15m away it will not do much ,will it !

 

[mike_s]

I'm thinking this temperature sensing pump sounds great and if it's quieter then that's better if it is to be timed to be on all day. I may suggest it if the noise is an issue.

 

[Nat]

Yeah it does work, we have done it before. Put it near the door to bathroom/kitchen etc, then have it on a 20min/30min run over then it shuts off. It works a treat and only comes on when someone enters the room.

I don't get this. What if you walk into the bathroom and go.straight to.hot.tap and.turn it on? The pump won't have had time.to circulate the.water and you'll still have to wait for the water to get hot completely negating the whole point of.having a.hot return. Or am I being thick?!

 

[tweakyboy]

you mean put the pump in the bathroom or put sensor there ? as if pump is in bathroom and there is more then one dead leg and the other shower is 10-15m away it will not do much ,will it !

Put the sensor just inside the doorway off the bathroom, by the time you run the tap you should have hot water. It should only take 10 odd seconds to circulate it around the pipework.

 

[SafeGasInstall]

i am with kev and nat on this one !

 

[ecowarm]

What is a PIR? Ecowarm why would the pump stay on once the tap was turned off?
Probably not the best idea after reading your thoughts, just thought there would be a better alternative to it being timed. I know it wouldn't be as quick on a flow switch but may still be an improvement I thought.

The cylinder and secondary circulation pump timeswitch are in the loft, maybe they would find this switch more convenient in the bathroom. I never installed the system.

I was replying to the OP's question regarding a flow switch

Just noticed you was the OP, sorry

 

[tweakyboy]

i am with kev and nat on this one !

It does work, promise!:egypt:

 

[Kev the gas]

Put the sensor just inside the doorway off the bathroom, by the time you run the tap you should have hot water. It should only take 10 odd seconds to circulate it around the pipework.

Sorry bud, that is the whole point of a Secondary return. 10 seconds ? of wasted water in a hotel/ large home is a lot of money.

The secondary pumps are nowhere near as powerful as whole house pumps/ shower pumps. Hence the reason they can be left running 24hrs a day without noise in a well designed system.

 

[tweakyboy]

Sorry bud, that is the whole point of a Secondary return. 10 seconds ? of wasted water in a hotel/ large home is a lot of money.

The secondary pumps are nowhere near as powerful as whole house pumps/ shower pumps. Hence the reason they can be left running 24hrs a day without noise in a well designed system.

Yeah I realise that it wouldn't work on a large home/hotel, the place we used it at was a very long cottage. The kitchen sink was about 5/6m away from the door, so by the time the sensor picked you up and got to the sink to run the hot tap there was hot water there.

I'm not saying it will work in every situation but its certainly something to keep hold of if you ever get into that situation.

 

[gil]

Hi, I'm new in this forum, and I have a secondary return problem. When we came to this house, there was a secondary return circuit. The secondary return covered the upstairs taps, and returned to a connection half-way down the cylinder. It was entirely gravity fed, but it worked pretty well.



Then the cylinder burst and the plumber who replaced it in a hurry fitted a cylinder without the half-way-down connection, and just cut off the secondary return circuit. It's been irritating to have cold water in the upstairs taps. I've finished my shave before it gets hot.



I have no intention of doing this myself, but I'd like to make sure the circuit is OK, before I talk to a plumber about it. It seemed to me that something like this would do the job. Any comments?

 

[SimonG]

Thats the standard way to do it when cylinder has no stand alone secondary return connection. Tee'd into cold feed.

 

[SafeGasInstall]

Wrong , sr should not mix with the cold water at all