- Secondary return for hot water,
or secondary hot water circulation.
My name's Allen Hart and in today's video,
we're going to look at secondary hot water returns
or secondary hot water circulation.
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Yeah, without further ado, let's get onto this video.
(upbeat music) (mouse clicks)
(bell dings)
What is a pumped hot water system
or pumped return and why would you need it?
So if you imagine a large house or a commercial property
or a hotel or hospital, et cetera, large premises,
if you imagine the boiler room, could be half a mile away.
And if you turn the hot tap on,
it take a very long time to get the hot water to the tap.
So what you need to do, you need
to make it so that when you turn the tap on,
the hot water comes out as soon as possible.
On small domestic systems, we tend to just put up
with the fact that it takes X amount of time.
But for instance, you've got a little bit
of a larger system, then you could put pumped return on.
And how that works, how a pump return works
for your hot water is if you imagine your
normal hot water cylinder, and you've got your hot water
that comes off, and your hot water comes off,
and so it's going in this direction...
and it's going off here towards bath.
And there's a little funny man in there, excuse my drawings.
What a secondary return does is it makes this like a loop.
So instead of having dead legs in system.
So if you imagine a normal system with this,
if this one connected here, when you run this bath here,
you've got to wait until you get all the hot water
from here, all the way around here, all the way around here,
all the way down there, and all the way to the bath.
But what this pump does when we connect this back up here...
these pumps or circulator, should I say,
and it circulates this water all the way around.
So it's going this way here, and then back this way,
and back, and back into the cylinder.
And I'll go through some of the calculations
of this, shortly.
So what that's doing is circulating this hot water,
so that when you open the tap,
the hot water is almost instant.
So it's a really, really good system,
especially for larger properties.
On top of the cylinder, this is the hot water outlet
and that goes to the hot tap.
And on this particular cylinder,
we've also got a hot water return.
So that's on a secondary return and we've got pump on here.
So that does a loop on the hot water circuit.
And that means that when they open the hot tap,
the hot water is almost instant.
So it's a lot better than waiting
for what could be a very, very long time.
This video is about hot water circulation,
just showing the principles of out works.
So just ignore the cylinder.
It's not showing you how we're selling the works,
at the moment.
I have done another video on how a cylinder works.
If you have a look here, if you click onto that,
it of tries to show you is as good as possible
how a hot water cylinder works.
Also if you haven't done so already, please put a thumbs up.
It really helps with the video and also,
if you could please add a comment below
'cause that helps with the video, as well.
This is the last job that I did
where we installed a secondary return for the hot water.
We removed the back, see?
Open vent heat on the boiler and we removed an old cylinder,
and then we replaced it with a Viessmann system boiler.
And we piped it with a Viessmann cylinder.
We piped up on a four pipe,
and then we put onto multi-zones.
So all the heating system was on multiple zones.
So like upstairs and downstairs
and the loft area was all in separate zones.
And the hot water was pumped, so it were a pump return.
And the reason we did that on that particular system was,
they had sinks and the sinks was quite far away.
And when they run, the hot tap on the sinks,
it took up all the ages and when I mean ages,
it seemed like five minutes, it took a long,
long time to get hot water to the sinks.
But once we updated the system, so we put the pump on,
we took a new pipe all the way around the system,
we lagged all the pipe, and we put proper circuit in.
And then once they open the tap then, it was almost instant,
and the customer was absolutely over the moon.
They really, really were really happy with that.
So again now, if we have a look at this, what we've got,
we've got this pump here and the pump
or the circular is normally operated by a time clock,
which only permits water to circulate around the system
when the building is occupied to sorta conserve energy.
The secondary turn pipe normally includes installation
of a non-return check valve near the pump.
And it's not shown, I've not shown it on here,
but you normally have a non-return valve on there.
And this connection here normally goes back
into the cylinder on the return
at about 25% down on the cylinder.
Normally when you buy an unvented cylinder,
you'll already have the connection to connect into for this.
Also, you can by selling those word for connection, as well.
Another thing to take note with this is we need
to use a special type of pump or a special type
of circulator and it's improved bronze circulator.
So you wouldn't be able to use your normal pump
that you have on your central heating system.
You need to use one that's Rus approved
and that is okay for hot water.
And on some systems, you may need
to update the expansion vessel.
So in larger systems, you may need a bigger expansion vessel
so that's just something to look out for, really.
Obviously, if it's an open hot water,
then you wouldn't need to, but you may need to
if it was an unvented cylinder or a sealed type system.
So that's just a little bit of an insight
into secondary turn for your hot water, how it works.
Hope you found this video of some use.
Please, if you have smashed that like button,
really appreciate that.
Just one thing to point out, I'm not a trainer,
I'm just trying my best to help new people
into the industry.
You do need to go on a training course
if you're gonna work on unvented cylinders.
Well, all cylinders now, anyway.
You need to go on a training course.
You need to have your qualifications to work on cylinders.
So please always go on the training courses,
and you're not allowed to work on unvented
for a lot of years unless you've got a qualification for it.
And we'll do some more videos on unvented cylinders shortly.
Yeah, I hope you found this video of some use.
Yeah, thanks for watching.