We recently had the landlord and plumber round to replace our immersion
heaters (plural - we're on economy 7) as both had packed up - the elements
had split and shorted.

When the plumber replaced them, he put in new thermostats. Ever since, the
hot water hasn't been as hot as it was before. It's most noticeable with
the shower. The plumber reckons it's a venturi-style mixer, and before the
work we used to have the dial about halfway round for a hot shower, now it's
just hot enough when turned to the hottest setting.

This is with the immersion thermostat turned up full.

We had the plumber back, and he flushed through various pipes in case there
was scale blocking the hot water pipes, all to no avail.

I've swapped the peak and off-peak thermostats (we never use peak), but it's
no better. I had the landlaord round, he ran his hand under the tap and
declared it fine. I brought home a digital thermocouple-type thermometer
from work and the hot tap gets to a maximum of 55.8°C in the morning when
the immersion heater is still on (running the tap for a few minutes).

The landlord brought round another thermostat to try, but the hot water gets
to the same temperature.

The thermostat is a Heatrae Sadia 7-inch one. The instructions say it comes
with the dial preset to 60°C, and it was somewhere in the middle. With it
turned all the way up, we get no hotter than 56°C.

We now don't know what to do - the landlord's getting annoyed at calling out
the plumber and not finidng out what's wrong, and we're getting annoyed with
warm showers.

Can anyone suggest something to try? Are there different sorts of
thermostats - could we get a hotter one? The ones we have audibly click in
the middle of the dial range at room temperature (i.e. out of the water
tank) - is that right?

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

In article , says...
We recently had the landlord and plumber round to replace our immersion=
=20
heaters (plural - we're on economy 7) as both had packed up - the element=
s=20
had split and shorted.
=20
When the plumber replaced them, he put in new thermostats. Ever since, =
the=20
hot water hasn't been as hot as it was before. It's most noticeable with=
=20
the shower. The plumber reckons it's a venturi-style mixer, and before t=
he=20
work we used to have the dial about halfway round for a hot shower, now i=
t's=20
just hot enough when turned to the hottest setting.
=20
This is with the immersion thermostat turned up full.
=20
We had the plumber back, and he flushed through various pipes in case the=
re=20
was scale blocking the hot water pipes, all to no avail.
=20
I've swapped the peak and off-peak thermostats (we never use peak), but i=
t's=20
no better. I had the landlaord round, he ran his hand under the tap and=
=20
declared it fine. I brought home a digital thermocouple-type thermometer=
=20
from work and the hot tap gets to a maximum of 55.8=B0C in the morning wh=
en=20
the immersion heater is still on (running the tap for a few minutes).
=20
The landlord brought round another thermostat to try, but the hot water g=
ets=20
to the same temperature.
=20
The thermostat is a Heatrae Sadia 7-inch one. The instructions say it co=
mes=20
with the dial preset to 60=B0C, and it was somewhere in the middle. With=
it=20
turned all the way up, we get no hotter than 56=B0C.
=20
We now don't know what to do - the landlord's getting annoyed at calling =
out=20
the plumber and not finidng out what's wrong, and we're getting annoyed w=
ith=20
warm showers.
=20
Can anyone suggest something to try? Are there different sorts of=20
thermostats - could we get a hotter one? The ones we have audibly click =
in=20
the middle of the dial range at room temperature (i.e. out of the water=
=20
tank) - is that right?
=20
=20

=09In my experience, the newer thermostats with the built-in=20
manually resettable over-temperature cut-outs, are made to control at a=20
much lower maximum temperature setting.

=09I suspect that it is to do with the recommendation that domestic=20
stored hot water is not maintained at a temperature higher than 65=B0C, to=
=20
minimise energy wastage due to heat losses.

=09The older type thermostats used to control upto about 85=B0C, so=20
the chances are that yours was set higher than recommended. The lower=20
temperature that you are reading at the tap is likely to be partly due=20
to heat losses in the delivery pipework.

=09The thermostat should not switch in its mid-point at room=20
temperature, perhaps it had not fully cooled from its time in the tank?=20
The fact that you have two stats that operate very closely to each other=20
indicates that they are unlikely to be faulty as such, unless they both=20
came from a faulty batch...

--=20
Regards,

Will.

Seems a pretty reasonable temp to me...If the out let is reading 55
then the tank itself must be sinificantly hotter.

A comfortable shower temp is around 40 so i reckon problem is the
shower itself not the tank temp per say. I know little about venturis
other than what they do, but maybe the work has in some way affected
the balance of hot/cold passing through...was anything else done at the
same time? was all lagging replaced around hot to shower pipes? this
can make a big difference on long pipe runs

ben

I brought home a digital thermocouple-type thermometer from work and the
hot tap gets to a maximum of 55.8°C in the morning when the immersion
heater is still on (running the tap for a few minutes).

Hot water cylinders without thermostatic mixing valves should be set to
between 55C and 60C. I would start looking at the shower, rather than try to
increase the temperature of the cylinder dangerously.

However, with regards the adjustment, you may be setting the overheat
cutout, rather than the working temperature. There should be two dials
(although one or the other might be fixed temp).

Christian.

In article ,=20
says...
I brought home a digital thermocouple-type thermometer from work and th=
e
hot tap gets to a maximum of 55.8=B0C in the morning when the immersion
heater is still on (running the tap for a few minutes).
=20
Hot water cylinders without thermostatic mixing valves should be set to
between 55C and 60C. I would start looking at the shower, rather than try=
to
increase the temperature of the cylinder dangerously.
=20
However, with regards the adjustment, you may be setting the overheat
cutout, rather than the working temperature. There should be two dials
(although one or the other might be fixed temp).
=20
Christian.
=20
=20
=20
=09I've not seen such a thermostat with an adjustable over-temp cut-
out, as far as I am aware, they are all factory preset.

--=20
Regards,

Will.

I've not seen such a thermostat with an adjustable over-temp cut-
out, as far as I am aware, they are all factory preset.

I'm fairly sure mine is adjustable, but I might have dreamt it. It's a heat
bank, so has to be set high, as the cylinder needs to run at higher temps
than a standard cylinder.

Christian.

"Ian Cowley" wrote in message
...
We recently had the landlord and plumber round to replace our immersion
heaters (plural - we're on economy 7) as both had packed up - the elements
had split and shorted.


Can anyone suggest something to try? Are there different sorts of
thermostats - could we get a hotter one? The ones we have audibly click
in the middle of the dial range at room temperature (i.e. out of the water
tank) - is that right?

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact


I recently got caught out as the thermostat needed to be turned
anticlockwise to increase the temperature - I had turned it clockwise and
couldn't see why the water as colder and then I got a torch and put my nose
on the floor:-)

Peter

In message , Will burbled:

The older type thermostats used to control upto about 85°C, so
the chances are that yours was set higher than recommended. The lower
temperature that you are reading at the tap is likely to be partly due
to heat losses in the delivery pipework.

The thermostat should not switch in its mid-point at room
temperature, perhaps it had not fully cooled from its time in the
tank? The fact that you have two stats that operate very closely to
each other indicates that they are unlikely to be faulty as such,
unless they both came from a faulty batch...

The thermostat that was switching at room temperature was the new one from
the box (which is now also giving 56°C water), so hadn't been near the tank
yet. That 56°C is measured at a tap close to the tank having run the tap
for a few minutes (to let the pipes heat up and everything).

I just think something's funny when I can't even get to the "factory preset"
temperature of 60°C when I have the thermostat up full.

is there a chance I might need an 11" thermostat? I don't know how big the
heater is, but I read somewhere that using the wrong thermostat can affect
its operation...?

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

In message , Christian
McArdle burbled:
I brought home a digital thermocouple-type thermometer from work and
the hot tap gets to a maximum of 55.8°C in the morning when the
immersion heater is still on (running the tap for a few minutes).

Hot water cylinders without thermostatic mixing valves should be set
to between 55C and 60C. I would start looking at the shower, rather
than try to increase the temperature of the cylinder dangerously.

However, with regards the adjustment, you may be setting the overheat
cutout, rather than the working temperature. There should be two dials
(although one or the other might be fixed temp).

The cut out is a little button that pops out, apparently at 90°C according
to the instructions! The thermostat is rated to operate at a "maximum
continuous head temperature" of 85°C according to the instructions. i can't
get it above 56!

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

In message , Peter Andrews
burbled:

I recently got caught out as the thermostat needed to be turned
anticlockwise to increase the temperature - I had turned it clockwise
and couldn't see why the water as colder and then I got a torch and
put my nose on the floor:-)

We tried turning it the other way and it definitely got even colder. I also
stuck a DVM in it to measure the resistance as I turned it

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

In article , says...
In message , Will burbled:

The older type thermostats used to control upto about 85=B0C, so
the chances are that yours was set higher than recommended. The lower
temperature that you are reading at the tap is likely to be partly due
to heat losses in the delivery pipework.

The thermostat should not switch in its mid-point at room
temperature, perhaps it had not fully cooled from its time in the
tank? The fact that you have two stats that operate very closely to
each other indicates that they are unlikely to be faulty as such,
unless they both came from a faulty batch...
=20
The thermostat that was switching at room temperature was the new one fro=
m=20
the box (which is now also giving 56=B0C water), so hadn't been near the =
tank=20
yet. That 56=B0C is measured at a tap close to the tank having run the t=
ap=20
for a few minutes (to let the pipes heat up and everything).
=20
I just think something's funny when I can't even get to the "factory pres=
et"=20
temperature of 60=B0C when I have the thermostat up full.
=20
is there a chance I might need an 11" thermostat? I don't know how big t=
he=20
heater is, but I read somewhere that using the wrong thermostat can affec=
t=20
its operation...?
=20
=20

=09You won't get an 11" stat into an 11" immersion heater, as the=20
pocket isn't long enough.

=09The problems occur when a 7" stat is put into an immersion heater=20
fitted vertically (or nearly vertically), as it switches the heater off=20
prematurely when the top "layer" of water reaches its set temperature.

=09Since your heater in use is the bottom one (or should be!) then a =20
7" stat is correct for the application...

--=20
Regards,

Will.

In article , says...
In message , Christian
McArdle burbled:
I brought home a digital thermocouple-type thermometer from work and
the hot tap gets to a maximum of 55.8=B0C in the morning when the
immersion heater is still on (running the tap for a few minutes).

Hot water cylinders without thermostatic mixing valves should be set
to between 55C and 60C. I would start looking at the shower, rather
than try to increase the temperature of the cylinder dangerously.

However, with regards the adjustment, you may be setting the overheat
cutout, rather than the working temperature. There should be two dials
(although one or the other might be fixed temp).
=20
The cut out is a little button that pops out, apparently at 90=B0C accord=
ing=20
to the instructions! The thermostat is rated to operate at a "maximum=20
continuous head temperature" of 85=B0C according to the instructions.

=09This is one part that you are misunderstanding - all that this is=20
saying is that the upper operating temperature limit of the environment=20
in which the stat may be installed is 85=B0C. Not that it is designed to=20
allow the water temperature to reach this level.

=09The replacement heaters that I have installed since the new type=20
stats were introduced have all been set to the maximum temperature=20
available, a number of people have noted that the water is not hot=20
enough. Nothing that can be readily done about it...

i can't=20
get it above 56!
=20
=20

--=20
Regards,

Will.

As you have access to a DVM, you could check each immersion heater itself.
They should about 20 Ohms resistance if it is a 3kWatt device. MAKE SURE THE
CIRCUIT IS DEAD FIRST.

If you can get to the top outlet of the immersion cylinder check the
temperature there. The copper should get to water temperature quite quickly.


With both cylinders in a luke warm condition, turn the setting dial from one
end to the other. You should hear a click as they open and close.

Measure the depth of the thermostat tube with a pice of stiff wire or thin
wooden dowel. If the immersion is fitted in the top of the cylinder the
thermostat tubes with be quite long, If they are fitted further down and
across the cylinder they will be quite short 7" or so.

Chris.


x-- 100 Proof News - http://www.100ProofNews.com
x-- 30+ Days Binary Retention with High Completion
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Ian Cowley expressed precisely :
is there a chance I might need an 11" thermostat? I don't know how big the
heater is, but I read somewhere that using the wrong thermostat can affect
its operation...?


--

With the thermostat removed, poke a piece of wire down inside the
thermostat pocket. The thermostat should be close to the depth of the
pocket and the element will be a little longer than the pocket.

If the element is mounted in the top of the tank, then it should be
quite long in length to enable it to heat the depths of the tank. A
shorter one would only heat the upper levels of the water.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

I measured the temperature of the water comming from the bath hot tap this
morning. The immersion was still on as that cuts out at 0800 hours. The
temperature came to 64deg Centigrade. My bath is directly above the
immersion cylinder with minimal pipework in between. I'm fairly sure that I
set the thermostat to 65 - 70 deg C. as I read that 68deg C is 'Scalding'
temperature.

Chris.


x-- 100 Proof News - http://www.100ProofNews.com
x-- 30+ Days Binary Retention with High Completion
x-- Access to over 1.9 Terabytes per Day - $8.95/Month
x-- UNLIMITED DOWNLOAD

In message , Will burbled:
The replacement heaters that I have installed since the new type
stats were introduced have all been set to the maximum temperature
available, a number of people have noted that the water is not hot
enough. Nothing that can be readily done about it...

So you're saying that recent (?) changes have introduced new, lower
temperature thermostats for efficiency/health and safety concerns, and that
I'm unlikely ever to get my hot water above 56°C ?

If so I shall go back to the plumber and demand back the money for the time
he spent aimlessly flushing non-existent scale out of the hot water pipes.
Any plumber worth his salt should've known that new thermostats are cooler
than old ones.

At the time I told him we didn't need new theermostats - I want the old one
back!

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

In article , says...
In message , Will burbled:
The replacement heaters that I have installed since the new type
stats were introduced have all been set to the maximum temperature
available, a number of people have noted that the water is not hot
enough. Nothing that can be readily done about it...
=20
So you're saying that recent (?) changes have introduced new, lower=20
temperature thermostats for efficiency/health and safety concerns, and th=
at=20
I'm unlikely ever to get my hot water above 56=B0C ?

=09In my experience, when the "new" type 'stats came into use, the=20
maximum settable temperature was significantly reduced. I have also=20
noted that the "new" type 'stats no longer have temperatures marked=20
thereon, replaced with a "+" and "-".

=09I have perused large amounts of "official" and "non-official"=20
websites trying to find a definitive statement regarding the allowable=20
settings on the 'stats, but have only found numerous recommendations=20
that the temperature be set to "about 60=B0C"

=09It occurred to me that since your thermostat probably switches=20
your immersion off at 2.30am or thereabouts, heat losses from the tank=20
may also account for the lower temperatures you are getting at the time=20
of usage.

=09I eventually found the following site, which ought to be of some=20
help in your situation...

http://www.sunvic.co.uk/rt.html

=09The VKL3201, which includes the over-temp. cutout, has a max.=20
setting of 70=B0C

=09The VKL2201, which it replaces, has a max. temp. setting 10=B0C=20
higher.

=09Any contractor fitting an old type 'stat is liable to prosecution=20
in the event of an accident or incident involving it. It is possible=20
that anyone fitting one themselves may be in the same position,=20
particularly if a third party is injured...

=20
If so I shall go back to the plumber and demand back the money for the ti=
me=20
he spent aimlessly flushing non-existent scale out of the hot water pipes=
..=20
Any plumber worth his salt should've known that new thermostats are coole=
r=20
than old ones.
=20
At the time I told him we didn't need new theermostats - I want the old o=
ne=20
back!
=20
=20

=09See above.

--=20
Regards,

Will.

All these replies are getting confusing!

Do you think the hot at the taps (not shower) is significantly cooler
than before?

If not then surely the shower is the issue? two different thermostats
giving same tank temp suggests tank temp itself is not the problem.
65degrees is steaming hot! if you are getting 56 at taps then my
opinion is shower/pipe run is the problem.

maybe a drop in mains pressure is preventing venturi from operating as
well. was the immersion replacement the only work done?

60-65 is the recommended temp for tank, you shouldn't need it higher
unless heat is being emitted over long pipe run. Lag those pipes!

In message ,
burbled:
All these replies are getting confusing!

Do you think the hot at the taps (not shower) is significantly cooler
than before?

If not then surely the shower is the issue? two different thermostats
giving same tank temp suggests tank temp itself is not the problem.
65degrees is steaming hot! if you are getting 56 at taps then my
opinion is shower/pipe run is the problem.

maybe a drop in mains pressure is preventing venturi from operating as
well. was the immersion replacement the only work done?

60-65 is the recommended temp for tank, you shouldn't need it higher
unless heat is being emitted over long pipe run. Lag those pipes!

Can't really decide if the hot water temperature is lower or not - it's just
bearably too hot at the moment, I think it was unbearably hot before.

The work carried out was to replace both immersion heaters and thermostats.
In the process there was a lot of draining of the tank (right down) and we
scopped out a lot of loose scale from the bottom of the tank (about 10
litres of scale flakes!). I think that's why the plumber thought that some
scale might have been blocking the hot water pipe to the venturi shower.

No noticeable drop in mains pressure.

Hmm, it looks like the new style thermostats are giving us lower
temperatures - anyone know where we can get old-style high-tem,perature
thermostats?


--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

On Fri, 5 Aug 2005 13:00:05 +0100, "Ian Cowley"
wrote:

Can't really decide if the hot water temperature is lower or not - it's just
bearably too hot at the moment, I think it was unbearably hot before.

The work carried out was to replace both immersion heaters and thermostats.
In the process there was a lot of draining of the tank (right down) and we
scopped out a lot of loose scale from the bottom of the tank (about 10
litres of scale flakes!). I think that's why the plumber thought that some
scale might have been blocking the hot water pipe to the venturi shower.

No noticeable drop in mains pressure.

Hmm, it looks like the new style thermostats are giving us lower
temperatures - anyone know where we can get old-style high-tem,perature
thermostats?

Hi,

If it's a venturi shower with mains pressure cold and a gravity fed
hot try closing the stop cock a bit temporarily to see if reduced cold
flow will give a hotter shower.

I doubt the landlord would want the HW system capable of producing
scalding hot water that could injure their tenant or their freinds and
relatives.

56C is about right for a maximum water temperatu

http://www.cornellaging.com/gem/product_consumer_scalds.html

cheers,
Pete.

In message , Pete C burbled:

If it's a venturi shower with mains pressure cold and a gravity fed
hot try closing the stop cock a bit temporarily to see if reduced cold
flow will give a hotter shower.

We tried that a few weeks ago - the shower temperature doesn't change all
the way down to shutting off the cold water entirely - at which point the
hot water also stops. My understanding of the physics is that if you have
less cold water flow it'll 'suck' less hot water from the tank - the result
is that the mixing ratio is the same.

By the way, we're in a first-floor flat. The hot water tank is in our flat,
so the head of water is really small - the shower head is at about the same
level as the top of the water tank. I think that's why the shower doesn't
get hotter with lessened cold water pressure - there's no flow of hot water
without the venturi effect.

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact

On Mon, 8 Aug 2005 10:22:17 +0100, "Ian Cowley"
wrote:

In message , Pete C burbled:

If it's a venturi shower with mains pressure cold and a gravity fed
hot try closing the stop cock a bit temporarily to see if reduced cold
flow will give a hotter shower.

We tried that a few weeks ago - the shower temperature doesn't change all
the way down to shutting off the cold water entirely - at which point the
hot water also stops. My understanding of the physics is that if you have
less cold water flow it'll 'suck' less hot water from the tank - the result
is that the mixing ratio is the same.

I see, fair enough.

By the way, we're in a first-floor flat. The hot water tank is in our flat,
so the head of water is really small - the shower head is at about the same
level as the top of the water tank. I think that's why the shower doesn't
get hotter with lessened cold water pressure - there's no flow of hot water
without the venturi effect.

The hot water pressure will be governed by the level in the cold water
tank the hot tank is fed from, which should be a bit higher up in the
attic.

Something else to check is to take the thermostat out, put it in a pan
of water, heat it up and see what temperature it opens. It's possible
the thermostat pocket has been bent towards the heating element or the
immersion heater orientated in such a way that the thermostat opens
prematurely.

Another potential problem is there may be strainers on the inlet to
the venturi shower that have been blocked with dislodged scale. If the
shower hose itself is quite narrow, or there is any scale blocking the
shower head that won't help either.

Something to try would be compare the hot flow just before the shower
mixer with a 1/2" hose siphoning from the same cold water tank that
feeds the hot tank, it should be at least as good.

If all else fails and the thermostat itself is faulty there are some
thermostats on this page that should do:

http://www.bes.ltd.uk/products/103.asp

However I'd set it to a sensible temperature using an decent
thermometer in a pan of water, rather than a dangerous temperature to
compensate for any problems. Otherwise there's a risk of people
getting injured later on for reasons you may not appreciate right now.

cheers,
Pete.

In message , Pete C burbled:

The hot water pressure will be governed by the level in the cold water
tank the hot tank is fed from, which should be a bit higher up in the
attic.

Unfortunately, the cold water doesn't come from the attic but a small header
tank on top of the hot water tank itself, which is fed from the mains. Thus
the head of water for the hot water is near ceiling level on our
single-level flat. Cold water for all taps seems to come straight from the
mains

Another potential problem is there may be strainers on the inlet to
the venturi shower that have been blocked with dislodged scale. If the
shower hose itself is quite narrow, or there is any scale blocking the
shower head that won't help either.

I'll check to see if there's any scale near the shower, but I think the
plumber did that the last time he spent ages looking for a problem.

I've installed an old-style thermostat my (electrician) father gave me at
the weekend. It has a temperature scale on the dial from 50 to 85 degrees
(rather than the lame + and - on the new ones). I set that last night and
this morning's water is 62°C versus 56°C the other day with the +/-
thermostat. As such the shower was decently hot with the dial on 3/4 of the
way round. So we're in a more sensible place for when the incoming cold
water starts to cool down in the autumn (i.e. there's adjustment on the
shower temperature now) and I might even up the stat a little more. the hot
water from the taps feels much more like it used to - unpleasantly hot
rather than the recent bearably-hot stuff we've had. I know there are
issues with having scalding water, but we've had that for the last 8 montsh
and we're happy with it

So it looks like it was a simple case of the new stats being colder than old
style ones. i now have a small stash of old style ones in case they ever
fail


--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact