Possible to replace Wilo warm water circulation pump?

[ppmoore]

Hello,

Our gas central heating boiler also provides hot water via a hot tank, located in the cellar. Becaue of the distance from the hot tank to the rest of the house, the hot water pipes are looped through the house to the kitchen and bathroom, and is driven by a circulation pump. This pump has now completelp seized.

I tested it, using the very helpful guide here:
http://www.youtube.com/watch?v=ECLQr3Z1pFk
The pump is a Wilo Z25, which I have now discoverd is very expensive. The cheapest online I've found is about £400. As far as I can tell, this also includes the brass flanges that connect the pump to the rest of the hot water system.

Is it possible to buy the motor, without having to buy the brass flange?

The Wilo Z25 pump is about 13 years old, and looking at the Wilo website, it seems that the following pumps are available: Z25/2, Z25/5, Z25/6 and Z25/10. I believ that the one I need is the Z25/2, because its power rating is about the same (~50W, single phase) as the old one I have.

Many thanks,
Paul

[Allan Mac]

On 9 Feb, 14:20, ppmoore <polom...@gmail.com> wrote:
> Hello,
>
> Our gas central heating boiler also provides hot water via a hot tank, located in the cellar. Becaue of the distance from the hot tank to the rest of the house, the hot water pipes are looped through the house to the kitchen and bathroom, and is driven by a circulation pump. This pump has now completelp seized.
>
> I tested it, using the very helpful guide here:http://www.youtube.com/watch?v=ECLQr3Z1pFk
> The pump is a Wilo Z25, which I have now discoverd is very expensive. The cheapest online I've found is about £400.

Looks like a bog standard CH pump to me. Search ebay for ch pump. The
first one I saw was 2 months old and at the moment is £15.00 That's
fifteen.

Allan

[Roger Mills]

I don't think you can use a bog standard CH pump in a (secondary) HW
system because the water is always changing - and you'll get corrosion
and/or contamination of the water. Don't you need one with bronze
innards, or somesuch? A CH pump is designed to circulate the *same*
water all the time in the primary circuit.

To the OP: What did your tests reveal? What you you mean by seized? Does
the impeller refuse to turn when you dismantle the pump, or does it look
like an electrical failure.

If, for example, the windings have burned out but the mechanical bits
are ok, you *may* be able to replace the electrics with those from a
cheaper pump. But if the mechanical bits are seized, you *will* need to
use components suitable for domestic hot water circulation.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

[Bob Minchin]

You can't normally swap the guts as the impeller needs to be bronze and
that is part of the motor.
toolstation part number 42168 should be similar to your original pump.

[harry]

You can't use a CH pump for domestic hot water, they just corrode up.
The real McCoy is made of bronze or stainless steel hence expensive.
Most manufacturers make one.

It is costing you lots of lost energy too. Maybe time for a re-
organisation.

[Tim+]

ppmoore <polo...@gmail.com> wrote:
> Hello,
>
> Our gas central heating boiler also provides hot water via a hot tank,
> located in the cellar. Becaue of the distance from the hot tank to the
> rest of the house, the hot water pipes are looped through the house to
> the kitchen and bathroom, and is driven by a circulation pump. This pump
> has now completelp seized.
>
> I tested it, using the very helpful guide here:

> http://www.youtube.com/watch?vìLQr3Z1pFk

> The pump is a Wilo Z25, which I have now discoverd is very expensive. The
> cheapest online I've found is about £400. As far as I can tell, this also
> includes the brass flanges that connect the pump to the rest of the hot water system.
>
> Is it possible to buy the motor, without having to buy the brass flange?
>
> The Wilo Z25 pump is about 13 years old, and looking at the Wilo website,
> it seems that the following pumps are available: Z25/2, Z25/5, Z25/6 and
> Z25/10. I believ that the one I need is the Z25/2, because its power
> rating is about the same (~50W, single phase) as the old one I have.
>
> Many thanks,
> Paul

How powerful does your pump need to be? As far as I'm aware you don't need
(or want) to circulate the water quickly. Would this pump do?

http://www.anchorpumps.com/grundfos-up-15-14b-80-comfort-hot-water-circulator-240v

Tim

[ppmoore]

Thanks all for the quick replies. Much appreciated.

The impeller has completely seized. I opened the venting screw on the front and tried using a screwdriver to coax some movement back into the impeller. No go. I then unscrewed the pump housing from the brass flange, and the impeller is completely seized.

The original idea behind the pump was to circulate water in the hot water circuit in the early morning and meal times, to avoid having to waste water when waiting for the hot water to "arrive". Silly enough, I never used the pump for the last 10 years, and only decided to start using it again when I noticed my water bill.

As far as I know, the pump doesn't need to actually deliver hot water, only to circulate it in the circuit just before use. So, I suppose it doesn't have to work very hard to do its job :<)

I suppose I have to use another Wilo pump with matching flange dimensions, as a drop-in replacement for the original.

I noticed a huge difference in prices (two from the UK, and one on Ebay in Germany):
http://www.pumpstock.co.uk/wilo-pumps-wilo-star-star-z-25-series.html
http://www.mytub.co.uk/product_information.php?product=531577
http://www.benl.ebay.be/itm/Wilo-Star-Z-25-2-Zirkulationspumpe-230-Volt-180-mm-Wasserpumpe-NEU-P286-13-/111008035150?pt=Systemkomponenten_Heizung&hash=item19d898314e

Is it possible that the last one on Ebay is a fake?

[Tim+]

ppmoore <polo...@gmail.com> wrote:
> Thanks all for the quick replies. Much appreciated.
>
> The impeller has completely seized. I opened the venting screw on the
> front and tried using a screwdriver to coax some movement back into the
> impeller. No go. I then unscrewed the pump housing from the brass flange,
> and the impeller is completely seized.
>
> The original idea behind the pump was to circulate water in the hot water
> circuit in the early morning and meal times, to avoid having to waste
> water when waiting for the hot water to "arrive". Silly enough, I never
> used the pump for the last 10 years, and only decided to start using it
> again when I noticed my water bill.

Water bill?

Do you mean water consumption bill? Okay, I suppose you waste a bit of
water running the taps waiting for your hot water but I would guess that
this will be less than the heat and power you waste by circulating your hot
water.


Tim

[ppmoore]

Hi Tim,

I'm sure you're right, but my wife pushing to reduce the water bill.
So, I thought, circulate the hot water in the morning 15 minutes before we get up to have our showers, and there shouldn't be too much wasted energy.

Certainly if I have to fork out £200 for a new pump, I probably wouldn't recuperate that outlay in my lifetime. On the other hand, I can see her point. Here in Belgium it seems the average water usage per person is about 100 litres per day, and ours is about 170. I even measured it recently: for a 10 minute shower and shave afterwards I use 130 litres.

P.

[harry]

On Feb 9, 9:02 pm, ppmoore <polom...@gmail.com> wrote:
> Thanks all for the quick replies. Much appreciated.
>
> The impeller has completely seized. I opened the venting screw on the front and tried using a screwdriver to coax some movement back into the impeller. No go. I then unscrewed the pump housing from the brass flange, and the impeller is completely seized.
>
> The original idea behind the pump was to circulate water in the hot water circuit in the early morning and meal times, to avoid having to waste water when waiting for the hot water to "arrive". Silly enough, I never used the pump for the last 10 years, and only decided to start using it again when I noticed my water bill.
>
> As far as I know, the pump doesn't need to actually deliver hot water, only to circulate it in the circuit just before use. So, I suppose it doesn't have to work very hard to do its job :<)
>
> I suppose I have to use another Wilo pump with matching flange dimensions, as a drop-in replacement for the original.
>

> I noticed a huge difference in prices (two from the UK, and one on Ebay in Germany):http://www.pumpstock.co.uk/wilo-pumps-wilo-star-star-z-25-series.htmlhttp://www.mytub.co.uk/product_information.php?product=531577http://www.benl.ebay.be/itm/Wilo-Star-Z-25-2-Zirkulationspumpe-230-Vo...

>
> Is it possible that the last one on Ebay is a fake?

Circulating domestic hot water is normally only necessary in large
commercial buildings.
Only enough water needs to be circulated to make up for the heat
losses from the pipework.
This depends on the size and length of the pipework and how well
insulated it is.
But the pump is very small. For a house, the smallest you can lay your
hands on.

Intermittant operation is a bad idea. Water that has been heated and
allowed to cool is very prone to bacterial contamination because the
chlorine (put in by the supplier)
has been driven out,
This is how people get leggionaire's disease for example.

[Tim+]

harry <harry...@btinternet.com> wrote:
> On Feb 9, 9:02 pm, ppmoore <polom...@gmail.com> wrote:
>> Thanks all for the quick replies. Much appreciated.
>>
>> The impeller has completely seized. I opened the venting screw on the
>> front and tried using a screwdriver to coax some movement back into the
>> impeller. No go. I then unscrewed the pump housing from the brass
>> flange, and the impeller is completely seized.
>>
>> The original idea behind the pump was to circulate water in the hot
>> water circuit in the early morning and meal times, to avoid having to
>> waste water when waiting for the hot water to "arrive". Silly enough, I
>> never used the pump for the last 10 years, and only decided to start
>> using it again when I noticed my water bill.
>>
>> As far as I know, the pump doesn't need to actually deliver hot water,
>> only to circulate it in the circuit just before use. So, I suppose it
>> doesn't have to work very hard to do its job :<)
>>
>> I suppose I have to use another Wilo pump with matching flange
>> dimensions, as a drop-in replacement for the original.
>>
>> I noticed a huge difference in prices (two from the UK, and one on Ebay in

>> Germany):http://www.pumpstock.co.uk/wilo-pumps-wilo-star-star-z-25-series.htmlhttp://www.mytub.co.uk/product_information.php?productS1577http://www.benl.ebay.be/itm/Wilo-Star-Z-25-2-Zirkulationspumpe-230-Vo...

>>
>> Is it possible that the last one on Ebay is a fake?
>
> Circulating domestic hot water is normally only necessary in large
> commercial buildings.
> Only enough water needs to be circulated to make up for the heat
> losses from the pipework.
> This depends on the size and length of the pipework and how well
> insulated it is.
> But the pump is very small. For a house, the smallest you can lay your
> hands on.
>
> Intermittant operation is a bad idea. Water that has been heated and
> allowed to cool is very prone to bacterial contamination because the
> chlorine (put in by the supplier)
> has been driven out,
> This is how people get leggionaire's disease for example.

Where's the chlorine going to go if the water is always inside the pipe
work?

Tim

[Terry Fields]

On Sat, 09 Feb 2013 14:48:56 -0800, ppmoore wrote:

> I'm sure you're right, but my wife pushing to reduce the water bill.
> So, I thought, circulate the hot water in the morning 15 minutes before
> we get up to have our showers, and there shouldn't be too much wasted
> energy.

It's clear where you are wasting water...

Try fitting a flow restrictor to your shower, it's simply a screw-on device. I reduced our showers here from 12 l/m
to 8 l/m with no noticeable difference in showering performance, but 6 /pm proved inadequate. Yours is 13 l/m.

Something like this:

http://www.eco-builder.co.uk/water-saving-devices/flow-restrictors/

If you both have a 10 minute shower a day, that's 260 litres of water; with a flow restrictor in place that would
come down to 160 litres, saving 100 litres a day or 3 cu metres a month. Taking shorter showers would save
even more.

Doing that alone, for little outlay and no inconvenience, would drop you way below the average consumption.

As for 'wasted' water, collect the cold that runs first and use it for other purposes, such as watering the garden or
washing cars. We store ours in 100-litre butts.

Replacing your pump seems like a costly idea that has no real benefit.

--
Terry Fields

[polygonum]

Much as the rest makes sense, I wonder about the collecting. How many
people here are set up to divert (by any means) the cold water that runs
first into a butt?

Can't help thinking that the materials and effort would rarely be worth
it. At least, beyond the trivial such as using the first bit to sluice
down the draining board or wash the spiders out of the bath... :-)

--
Rod

[Terry Fields]

It takes 1 minute before the shower flow temperature stabilises, and we collect that water in a 10-litre plastic
container. We simply take these outside and empty them into the butts.

Collecting 20 litres a day for the period of March to September saves about £25 in water costs (see below).

> Can't help thinking that the materials and effort would rarely be worth
> it. At least, beyond the trivial such as using the first bit to sluice
> down the draining board or wash the spiders out of the bath... :-)

Ah, well, paying a combined cost of ~£6:50 a cubic meter for water and sewerage concentrates the mind on
water-saving measures...

The two of us here average 7.8 cu m a month, or about £650 a year including standing charges; most of that
goes in showers and toilet flushes. Any fewer toilet flushes and the system blocks due to inadequate flow at a
junction in the pipework.


--
Terry Fields

[polygonum]

Having finally got our water leak issues fully resolved (not much thanks
to a major water company that services much of London), I had a scribble
calculation of the amount lost. I am convinced it is well north of half
a million litres - and that is only considering the time since we
realised there was a leak. A lower level of leakage could have been
going on for years.

Luckily no meter. :-)

But the idea of carrying a 10 l bucket (or whatever) downstairs and out
in the freezing cold is extremely unappealing. Indeed, my partner could
not physically do it. Sure I could do it when I am around but still not
easy. Our small bathroom, for example, really has nowhere to keep a
suitable container.

--
Rod

[ARW]

harry wrote:
>
> Circulating domestic hot water is normally only necessary in large
> commercial buildings.
> Only enough water needs to be circulated to make up for the heat
> losses from the pipework.
> This depends on the size and length of the pipework and how well
> insulated it is.
> But the pump is very small. For a house, the smallest you can lay your
> hands on.
>
> Intermittant operation is a bad idea. Water that has been heated and
> allowed to cool is very prone to bacterial contamination because the
> chlorine (put in by the supplier)
> has been driven out,
> This is how people get leggionaire's disease for example.

How does this differ from the HW water left in the pipework between the
water cylinder and the tap that cools down in a normal HW setup?

--
Adam

[Onetap]

On Saturday, February 9, 2013 2:20:06 PM UTC, ppmoore wrote:
> Hello,

It's a 10 minute job for anyone competent with soldering or compression fittings to put different pump fittings in. I'd get a replacement pump and alter the pipes to suit.

Alternative 1: it is probably limescale. Remove pump, dismantle and remove electric bits. Immerse in weak descaling solution for 12 hours or so. If it then works, you're better off. If it's still knackered, you're no worse off.

Make sure there's a working NRV on the return to ensure limescale particles don't get dragged out of the cylinder. When there's a draw off, the flow direction in the return will reverse, if it can.

Alternative 2; you should need very, very little circulating head for a HWS secondary system. Gravity circulation will work adequately for some systems (depending on the heat loss and pipe insulation). Make up a blanking piece of straight pipe to replace the pump and try it with no pump. If there's a lot of heat loss from the pipes, it's a non-starter.

[Roger Mills]

On 09/02/2013 17:29, Bob Minchin wrote:

> Roger Mills wrote:

>> I don't think you can use a bog standard CH pump in a (secondary) HW
>> system because the water is always changing - and you'll get corrosion
>> and/or contamination of the water. Don't you need one with bronze
>> innards, or somesuch? A CH pump is designed to circulate the *same*
>> water all the time in the primary circuit.
>>
>> To the OP: What did your tests reveal? What you you mean by seized? Does
>> the impeller refuse to turn when you dismantle the pump, or does it look
>> like an electrical failure.
>>
>> If, for example, the windings have burned out but the mechanical bits
>> are ok, you *may* be able to replace the electrics with those from a
>> cheaper pump. But if the mechanical bits are seized, you *will* need to
>> use components suitable for domestic hot water circulation.

> You can't normally swap the guts as the impeller needs to be bronze and
> that is part of the motor.

I don't think I've ever dismantled one, but the video which the OP cited
appeared to show all the mechanical bits (impeller, shaft and shaft
case) coming out from the centre of the windings.

[Roger Mills]

On 09/02/2013 22:48, ppmoore wrote:
>
>
> Hi Tim,
>
> I'm sure you're right, but my wife pushing to reduce the water bill.
> So, I thought, circulate the hot water in the morning 15 minutes before we get up to have our showers, and there shouldn't be too much wasted energy.
>
> Certainly if I have to fork out £200 for a new pump, I probably wouldn't recuperate that outlay in my lifetime. On the other hand, I can see her point. Here in Belgium it seems the average water usage per person is about 100 litres per day, and ours is about 170. I even measured it recently: for a 10 minute shower and shave afterwards I use 130 litres.
>
> P.

How long is the pipe between hot water cylinder and shower? Even if it's
22mm pipe, you will only use about 1 litre per 3 metres of pipe waiting
for it to get hot - so that's unlikely to be your problem.

Your problem is clearly profligate waste of water! *No-one* needs the
shower on full blast for 10 minutes in order to get a decent shower! Try
turning it on to wet yourself and then turn it off while you soap
yourself, and then back on to wash the soap off. I would struggle to
make the whole process last more than *five* minutes - if that.

Oh, and fit a flow restrictor - as others have suggested.

Just replacing your circulation pump will achieve diddly squat!

[Terry Fields]

On Sun, 10 Feb 2013 11:04:23 +0000, polygonum wrote:

> Luckily no meter.

Stay that way!

> But the idea of carrying a 10 l bucket (or whatever) downstairs and out
> in the freezing cold is extremely unappealing. Indeed, my partner could
> not physically do it. Sure I could do it when I am around but still not
> easy. Our small bathroom, for example, really has nowhere to keep a
> suitable container.

We don't collect shower water over the Autumn to Spring periods, there's enough rainfall to fill buckets, etc.

The place to keep the 10-litre container is in the bath/shower. Lift it out when the water gets to temperature, and
take it outside to empty into the butts on the next journey outside.

As I said, water/sewerage at £650 a year for two careful users concentrates the mind!

--
Terry Fields

[harry]

There's more of it. It's not all washed away by running the tap for a
while.

[ARW]

OK and how does the chlorine encourage the bacterial growth?

--
Adam

[ppmoore]

Again, many thanks for the replies.

The hot water circuit/loop has a blocking return valve (if that's what it's called) beside the tank. This stops the hot water from the hot tank circulating in the circuit due to natural convection, which I'm sure would cost a lot more, even with the pipes being lagged. This ensures that the water can only be circulated when the pump is switched on.

I'm coming around to the idea that installed a new pump costing upwards of £150 on Ebay is a frivolous idea, just to save a few tens of litres of water per day.
I could instead either:
- take out and bypass the pump and ensure that the return valve is set to open, in which natural convection should ensure that there is always warm water available in the circuit - probably an expensive option
- take out and bypass the pump and ensure that the return valve is set to blocking, to stop the circulation by convection
- just leave the pump in place, in which case the blocked impeller will stop the circulation by convection

Now just have to convince the better half...

P

[harry]

It's the lack of chlorine encourages bacterial growth.
So the greater the volume of unchlorinated water the more bugs you
get. When the pump is started after being off for a while, they are
all pumped back into the tank/system.
And mixed in so running the tap doesn't help.
If you have a pump at all, the only way to get round all this is to
have it running constantly. Very expensive energy wise.

[Terry Fields]

On Sun, 10 Feb 2013 12:25:24 -0800, ppmoore wrote:

> Again, many thanks for the replies.
>
> The hot water circuit/loop has a blocking return valve (if that's what
> it's called) beside the tank. This stops the hot water from the hot tank
> circulating in the circuit due to natural convection, which I'm sure
> would cost a lot more, even with the pipes being lagged. This ensures
> that the water can only be circulated when the pump is switched on.
>
> I'm coming around to the idea that installed a new pump costing upwards
> of £150 on Ebay is a frivolous idea, just to save a few tens of litres
> of water per day.
> I could instead either:
> - take out and bypass the pump and ensure that the return valve is set
> to open, in which natural convection should ensure that there is always
> warm water available in the circuit - probably an expensive option -
> take out and bypass the pump and ensure that the return valve is set to
> blocking, to stop the circulation by convection - just leave the pump in
> place, in which case the blocked impeller will stop the circulation by
> convection
>
> Now just have to convince the better half...

You need to decide whether you want to save water (your original post) or save energy (which is what you seem
to be talking about), do both, or keep SWMBO happy.

Circulating hot water round a system just in case you want some hot water from a tap seems to be swapping
less water usage for greater energy usage.You'll need to calculate the cost of the losses on each and decide
which is the least; or if your only target is water saving, how much water will replacing the pump save in terms of
cost - from which you can work out how long it would take to pay you back.

Frankly, adding a flow restrictor and taking 5 minute showers would save you far more energy and water than
gained by replacing the pump, which if you didn't replace would save you even more.

Of course, if it's a matter of doing what SWMBO wants, then like the rest of us, you're stuffed. Good luck.

--
Terry Fields

[Dave Liquorice]

On Mon, 11 Feb 2013 00:14:45 -0800 (PST), harry wrote:

> It's the lack of chlorine encourages bacterial growth.
> So the greater the volume of unchlorinated water the more bugs you
> get. When the pump is started after being off for a while, they are
> all pumped back into the tank/system. And mixed in so running the tap
> doesn't help. If you have a pump at all, the only way to get round all
> this is to have it running constantly. Very expensive energy wise.

Or ensure that the water in the tank is regulary heated to >60 C (?) and
that this scalding water is circulated. ^0C is really rather too hot to
have coming out of the taps so a thermostic mixer would need to be fitte
on the tank out put to bring the temp down to safe levels.

Circulating hot water is going to cost money for the energy lost and the
electricty used. The 10l per shower water "saved" will never cover those
costs. What is that about 3 quid per hundred showers, or about 2 months
with two showers per day.

--
Cheers
Dave.

[harry]

On Feb 11, 10:09 am, "Dave Liquorice" <allsortsnotthis...@howhill.com>
wrote:

> On Mon, 11 Feb 2013 00:14:45 -0800 (PST), harry wrote:
> > It's the lack of chlorine encourages bacterial growth.
> > So the greater the volume of unchlorinated water the more bugs you
> > get. When the pump is started after being off for a while, they are
> > all pumped back into the tank/system. And mixed in so running the tap
> > doesn't help. If you have a pump at all, the only way to get round all
> > this is to have it running constantly. Very expensive energy wise.
>
> Or ensure that the water in the tank is regulary heated to >60 C (?) and

> that this scalding water is circulated. 60C is really rather too hot to

> have coming out of the taps so a thermostic mixer would need to be fitte
> on the tank out put to bring the temp down to safe levels.
>

That's exactly what is done in hospitals.
Cost an absolute fortune when the Leggionaires thing came out. Both in
terms of altering pipework and running costs.

[ppmoore]

Terry,

I think you've nailed it right on the head.

Thanks again.