secondary return hot water

[tomsim]

When fitting a secondary return to a large domestic property is it usual to tee the return in to the hot a one point? Or more than once? Is it usualy tee'd in at a hot draw off furthest from the hot water cylinder?

 

[buck51]

Normally as close as you can to each draw off point, and with a lockshield on each return.

 

[Biggles..]

Within 1 meter of outlet and each outlet.

 

[picasso]

Whats the idea of the lockshield valve ?

 

[Dan Robinson]

Balance each one same as a heating circuit.

 

[Biggles..]

Balancing to avoid short circuiting, you want flow at all points.

 

[picasso]

How does that work ? if you have a loop from cylinder take off back to say the cold feed (unvented for example) the water is just going in a circle, so what changes concerning the loop when you open a tap ?

 

[Biggles..]

Nothin changes.

The idea is that as soon as you open a tap you have hot water.

You need it to go to the furthest point as its never installed as a perfect circle.

 

[Onetap]

Balancing to avoid short circuiting, you want flow at all points.

There are TRV-type valves available for HWS for this application; they sense the water temperature (not the air temperature as do TRVs) and close down as the water heats up. They're useful for big systems with a variable speed pump.

E.g.,
http://heating.danfoss.co.uk/xxTypex/209446_MNU17431795_SIT313.html

 

[ALEC1]

the lock shield valves are only used if there are branches or it is not one continuos loop....

pumps too have sensors and shut down if the return reaches a certain temperature...

 

[Agile]

For casual readers it may help if I point out that there are some different applications being discussed here.

The return from each hot outlet is mostly used in hotels etc.

But most domestic properties only have a single loop for the whole house or for each floor.

Tony

 

[Biggles..]

Balancing to avoid short circuiting, you want flow at all points.

There are TRV-type valves available for HWS for this application; they sense the water temperature (not the air temperature as do TRVs) and close down as the water heats up. They're useful for big systems with a variable speed pump.

E.g.,
http://heating.danfoss.co.uk/xxTypex/209446_MNU17431795_SIT313.html[/QUOTE]

Can't think of the ones we've used lately. They aren't danfos but exactly the same thing. You set the temp on the head an there's a little dial to prove your return water temp.

More beneficial to long drops, say in vertical voids. We used them in a hotel refurb.wouldnt fir them for single outlets etc as no point in Te cost.

Have to look under the office desk later as I've got loads left.