I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?
--

Mike

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet and you might
need a pressure regulator to bring your mains water pressure down to
something that the boiler will cope with. They seem to last 5-7 years.

Otherwise you will find it leaks/drips overnight when the water pressure
is at its highest. Apart from that they are relatively trouble free.

Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

Decent ones at 3kW need a bit too much power for that. Proper flash
boilers that do hot water on demand need even more power to work.

--
Regards,
Martin Brown

On Wed, 31 Mar 2021 16:56:09 +0100, Martin Brown
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet and you might
need a pressure regulator to bring your mains water pressure down to
something that the boiler will cope with. They seem to last 5-7 years.

Otherwise you will find it leaks/drips overnight when the water pressure
is at its highest. Apart from that they are relatively trouble free.

Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

Decent ones at 3kW need a bit too much power for that. Proper flash
boilers that do hot water on demand need even more power to work.

Really informative, thanks Martin. Considering all that, I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.
--

Mike

On 31/03/2021 17:11, Mike Halmarack wrote:
On Wed, 31 Mar 2021 16:56:09 +0100, Martin Brown
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet and you might
need a pressure regulator to bring your mains water pressure down to
something that the boiler will cope with. They seem to last 5-7 years.

Otherwise you will find it leaks/drips overnight when the water pressure
is at its highest. Apart from that they are relatively trouble free.

Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

Decent ones at 3kW need a bit too much power for that. Proper flash
boilers that do hot water on demand need even more power to work.

Really informative, thanks Martin. Considering all that, I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.


Are you in a hard water area ?. If so, you need to think about how
you will descale it from time to time.

On Wed, 31 Mar 2021 17:17:39 +0100, Andrew
wrote:

On 31/03/2021 17:11, Mike Halmarack wrote:
On Wed, 31 Mar 2021 16:56:09 +0100, Martin Brown
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet and you might
need a pressure regulator to bring your mains water pressure down to
something that the boiler will cope with. They seem to last 5-7 years.

Otherwise you will find it leaks/drips overnight when the water pressure
is at its highest. Apart from that they are relatively trouble free.

Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

Decent ones at 3kW need a bit too much power for that. Proper flash
boilers that do hot water on demand need even more power to work.

Really informative, thanks Martin. Considering all that, I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.


Are you in a hard water area ?. If so, you need to think about how
you will descale it from time to time.

Spot on Andrew! You should see the outside of our kettle, let alone
the inside.
--

Mike

On 31/03/2021 17:22, Mike Halmarack wrote:
On Wed, 31 Mar 2021 17:17:39 +0100, Andrew
wrote:

On 31/03/2021 17:11, Mike Halmarack wrote:
On Wed, 31 Mar 2021 16:56:09 +0100, Martin Brown
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet and you might
need a pressure regulator to bring your mains water pressure down to
something that the boiler will cope with. They seem to last 5-7 years.

Otherwise you will find it leaks/drips overnight when the water pressure
is at its highest. Apart from that they are relatively trouble free.

Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

Decent ones at 3kW need a bit too much power for that. Proper flash
boilers that do hot water on demand need even more power to work.

Really informative, thanks Martin. Considering all that, I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.


Are you in a hard water area ?. If so, you need to think about how
you will descale it from time to time.

Spot on Andrew! You should see the outside of our kettle, let alone
the inside.

Ah, the wonders of hard-water areas. We are in a very soft water area
and a 20 year old kettle looks like new inside. In fact the water
treatment plants have to add phosphates to stop the soft water
dissolving the (very clean) inside surfaces of old lead pipes.

On Wed, 31 Mar 2021 17:11:54 +0100, Mike Halmarack
wrote:

snip

I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.

A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash

And hasn't regretted it for a second.

It was easy to install, didn't necessitate having to modify the
existing tap feeds and can be run as long / often as he needs (which
has turned out to be quite a lot because it's a shop that's considered
an essential service so open during lockdown and Covid itself).

He said it's at full hand washing temp in about 5-6 seconds but as
it's a spray that's not a lot of water. And that's why I was
interested in something like that as my bathroom hand basin feed is
reasonably long from the multipoint gas water heater, in 22mm copper
(for the bath when there was going to be indirect HW cylinder there)
and whilst we aren't on a water meter (yet), do try not to waste any
if possible.

Cheers, T i m

On Wed, 31 Mar 2021 17:45:18 +0100, T i m wrote:

On Wed, 31 Mar 2021 17:11:54 +0100, Mike Halmarack
wrote:

snip

I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.

A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash

And hasn't regretted it for a second.

It was easy to install, didn't necessitate having to modify the
existing tap feeds and can be run as long / often as he needs (which
has turned out to be quite a lot because it's a shop that's considered
an essential service so open during lockdown and Covid itself).

He said it's at full hand washing temp in about 5-6 seconds but as
it's a spray that's not a lot of water. And that's why I was
interested in something like that as my bathroom hand basin feed is
reasonably long from the multipoint gas water heater, in 22mm copper
(for the bath when there was going to be indirect HW cylinder there)
and whilst we aren't on a water meter (yet), do try not to waste any
if possible.

Cheers, T i m


Crikey! Yet more unexpected possibilities for consideration.
--

Mike

On Wed, 31 Mar 2021 17:53:40 +0100, Mike Halmarack
wrote:

snip
A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash


Crikey! Yet more unexpected possibilities for consideration.

Oh, forgot to mention, we are also in a fairly hard water area.

Cheers, T i m

On 31 Mar 2021 at 17:45:18 BST, "T i m" wrote:

On Wed, 31 Mar 2021 17:11:54 +0100, Mike Halmarack
wrote:

snip

I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.

A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash

And hasn't regretted it for a second.

It was easy to install, didn't necessitate having to modify the
existing tap feeds and can be run as long / often as he needs (which
has turned out to be quite a lot because it's a shop that's considered
an essential service so open during lockdown and Covid itself).

He said it's at full hand washing temp in about 5-6 seconds but as
it's a spray that's not a lot of water. And that's why I was
interested in something like that as my bathroom hand basin feed is
reasonably long from the multipoint gas water heater, in 22mm copper
(for the bath when there was going to be indirect HW cylinder there)
and whilst we aren't on a water meter (yet), do try not to waste any
if possible.


Thing is, it'd need hot water storage if doing anything other than hand
washing. And unless you can choreograph everything neatly, that's going to
increase running costs a lot.

The idea does appeal to me - using a combi to heat small amounts seems very
inefficient, wasting water. Although the money cost of gas cost is a lot less
than electric (about a quarter).

--
Cheers, Rob

On Thu, 1 Apr 2021 08:17:54 +0000 (UTC), RJH
wrote:

On 31 Mar 2021 at 17:45:18 BST, "T i m" wrote:

On Wed, 31 Mar 2021 17:11:54 +0100, Mike Halmarack
wrote:

snip

I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.

A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash

And hasn't regretted it for a second.

It was easy to install, didn't necessitate having to modify the
existing tap feeds and can be run as long / often as he needs (which
has turned out to be quite a lot because it's a shop that's considered
an essential service so open during lockdown and Covid itself).

He said it's at full hand washing temp in about 5-6 seconds but as
it's a spray that's not a lot of water. And that's why I was
interested in something like that as my bathroom hand basin feed is
reasonably long from the multipoint gas water heater, in 22mm copper
(for the bath when there was going to be indirect HW cylinder there)
and whilst we aren't on a water meter (yet), do try not to waste any
if possible.


Thing is, it'd need hot water storage if doing anything other than hand
washing.

Well for my mate in the shop and us at home for the hand basin, as
instant as possible hot water, hot enough to wash hands is about all
we need. Eg, he doesn't do much washing up (just rinses his cup now
and again) as he brings sarnies in from home in a Tupperware box
(trying to eat hot food when running a retail shop on you own isn't
easy).

And unless you can choreograph everything neatly, that's going to
increase running costs a lot.

Oh, sure but see above.

For us we would retain the Multipoint hot water supply so would still
have continuous hot water there if we could efficiently consume the
initial cold (like when running a bath).

The idea does appeal to me - using a combi to heat small amounts seems very
inefficient, wasting water.

That's my main bugbear, especially when it's not been run for a while.

Although the money cost of gas cost is a lot less
than electric (about a quarter).

True, but I also feel guilty about wasting perfectly good drinking
quality water (even though we aren't on a meter). ;-(

If it was the smaller (3kW) one and you could get easy access to both
the water supply (above the sink) and electricity (I have on the other
side of the wall) then if use alongside any existing solution, should
give you the best of both worlds?

Given we now have and are enjoying quite a bit of home automation now
(automatic lights in the hall, landing and kitchen), I think I might
like the idea of an 'automatic' hand wash water heater, subject to
being able to use the existing taps without triggering it etc.

Cheers, T i m

On 01/04/2021 09:17, RJH wrote:
On 31 Mar 2021 at 17:45:18 BST, "T i m" wrote:
On Wed, 31 Mar 2021 17:11:54 +0100, Mike Halmarack
wrote:

snip

I think I
would prefer to go for the flash/instantaneous option, even though the
power supply would need to be hard wired.

A mate replaced the 'boiler' type water heater for an instant oversink
type in his shop:

https://www.tritonshowers.co.uk/t30i-handwash

And hasn't regretted it for a second.

It was easy to install, didn't necessitate having to modify the
existing tap feeds and can be run as long / often as he needs (which
has turned out to be quite a lot because it's a shop that's considered
an essential service so open during lockdown and Covid itself).

He said it's at full hand washing temp in about 5-6 seconds but as
it's a spray that's not a lot of water. And that's why I was
interested in something like that as my bathroom hand basin feed is
reasonably long from the multipoint gas water heater, in 22mm copper
(for the bath when there was going to be indirect HW cylinder there)
and whilst we aren't on a water meter (yet), do try not to waste any
if possible.


Thing is, it'd need hot water storage if doing anything other than hand
washing. And unless you can choreograph everything neatly, that's going to
increase running costs a lot.

The idea does appeal to me - using a combi to heat small amounts seems very
inefficient, wasting water. Although the money cost of gas cost is a lot less
than electric (about a quarter).

The cheapest way is to boil a kettle. A kettleful of boiling water is
enough for washing up/hand washing clothes, once diluted with cold.

--
Max Demian

On 31/03/2021 16:56, Martin Brown wrote:
On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running until
it gets hot. There is only 25L of hot water available and when it is
gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet

I am sure that I have seen some that don't have to have overflows or
vents. They work by allowing expansion due to heating to push back into
the inlet pipe - the limited volume of expansion not being in any danger
of pushing warm water back into any other leg.

On 31/03/2021 20:31, Steve Walker wrote:
On 31/03/2021 16:56, Martin Brown wrote:
On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in. They
are fine so long as you don't turn the tap on and leave it running
until it gets hot. There is only 25L of hot water available and when
it is gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet

I am sure that I have seen some that don't have to have overflows or
vents. They work by allowing expansion due to heating to push back into
the inlet pipe - the limited volume of expansion not being in any danger
of pushing warm water back into any other leg.

Ah, there we go.

https://www.plumbnation.co.uk/site/a...-water-heater/

On 31/03/2021 22:49, Steve Walker wrote:
On 31/03/2021 20:31, Steve Walker wrote:
On 31/03/2021 16:56, Martin Brown wrote:
On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

The ones in our VH are 25L capacity 3kW so best off hardwired in.
They are fine so long as you don't turn the tap on and leave it
running until it gets hot. There is only 25L of hot water available
and when it is gone it takes a while to heat back up again.

Things to watch are you will need an overflow/vent outlet

I am sure that I have seen some that don't have to have overflows or
vents. They work by allowing expansion due to heating to push back
into the inlet pipe - the limited volume of expansion not being in any
danger of pushing warm water back into any other leg.

Ah, there we go.

https://www.plumbnation.co.uk/site/a...-water-heater/

ISTR the problems arise the moment that you have to put in a pressure
reducing valve. I don't see a maximum rated mains pressure on that one.

Our VH water supply is roughly 4bar going on 5bar at night in winter.
The water heaters are rated 3.5 bar maximum working pressure.
(hidden in the small print somewhere)

Once you need a NRV, expansion chamber and pressure reducer to install
them it becomes quite a complicated installation under the sink space.

--
Regards,
Martin Brown

Mike Halmarack wrote:

I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

Someone in another group fitted an electric boiler that stores energy
using a phase-change material, he seemed much happier with it than I
expected.

https://sunamp.com

On Wed, 31 Mar 2021 18:13:47 +0100, Andy Burns
wrote:

Mike Halmarack wrote:

I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

Someone in another group fitted an electric boiler that stores energy
using a phase-change material, he seemed much happier with it than I
expected.

https://sunamp.com

So what's inside, some storage heater bricks wrapped with copper pipe?
;-)

Cheers, T i m

On 31/03/2021 18:25, T i m wrote:
On Wed, 31 Mar 2021 18:13:47 +0100, Andy Burns
wrote:

Mike Halmarack wrote:

I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

Someone in another group fitted an electric boiler that stores energy
using a phase-change material, he seemed much happier with it than I
expected.

https://sunamp.com

So what's inside, some storage heater bricks wrapped with copper pipe?
;-)

Cheers, T i m


A Lirpa Loof ?

On Wed, 31 Mar 2021 18:13:47 +0100, Andy Burns
wrote:

Mike Halmarack wrote:

I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

Someone in another group fitted an electric boiler that stores energy
using a phase-change material, he seemed much happier with it than I
expected.

https://sunamp.com

Yes but is it any less expensive than plastic surgury?
--

Mike

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?



Mike

How much water do you need for a washing up bowl? 5 litres, 10 litres?

A 3kw instantaneous water heater only delivers around 1 litre of hand
hot water per minute. So, it will take you 5-10 minutes to fill the
washing up bowl. Are you okay with that?

That's for water coming in at 5C, and washing up water at 50C.

On Wed, 31 Mar 2021 20:51:40 +0100, GB
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?



Mike

How much water do you need for a washing up bowl? 5 litres, 10 litres?

A 3kw instantaneous water heater only delivers around 1 litre of hand
hot water per minute. So, it will take you 5-10 minutes to fill the
washing up bowl. Are you okay with that?

That's for water coming in at 5C, and washing up water at 50C.

If that be so, an irksome non-solution.
--

Mike

On Thu, 01 Apr 2021 08:53:30 +0100, Mike Halmarack
wrote:

On Wed, 31 Mar 2021 20:51:40 +0100, GB
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?



Mike

How much water do you need for a washing up bowl? 5 litres, 10 litres?

A 3kw instantaneous water heater only delivers around 1 litre of hand
hot water per minute. So, it will take you 5-10 minutes to fill the
washing up bowl. Are you okay with that?

That's for water coming in at 5C, and washing up water at 50C.

If that be so, an irksome non-solution.

I think it may depend on what the (worst case) goal of the solution
needs to cover?

If it includes actually *needing* a bowl full of washing-up
temperature water several times a day than anything 'instant' is going
to have to be pretty powerful, as is any local water store, if not
either quite high capacity or high power (for reasonable recovery
time).

I've no idea how powerful our balanced flu combi-boiler-sized
multipoint water heater is but even that would take quite a time to
fill a basin with hot water (mainly the time taken to get the hot
water to the basin) and a fair time to fill even a corner bath, as
does the combi boiler in daughters flat (where you start the bath
running then go and do something else for a good time).

When having baths at Mums years ago with a big HW cylinder you could
run a bath pretty quickly (all be it only one without waiting ages).

And if you were suggesting filling a kettle with hot water from any
such hot water source, I'm not sure what advantage that would be other
than saving time?

There isn't anything much more efficient than a kettle (the element in
direct contact with what it's heating in a reasonably insulated
(plastic?) container) and so likely more efficient than heating and
storing the water to use later or from an instant heater (unless gas
because of the potentially cheaper energy costs).

If you are talking of washing crockery, depending on how much and how
heavy the soiling (baked on stuff that might appreciate being soaked),
I wonder if Jeff could test / vouch for how practical it might be to
wash a plate under the instant hand washer?

Cheers, T i m

On Thu, 01 Apr 2021 09:36:10 +0100, T i m wrote:

On Thu, 01 Apr 2021 08:53:30 +0100, Mike Halmarack
wrote:

On Wed, 31 Mar 2021 20:51:40 +0100, GB
wrote:

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?



Mike

How much water do you need for a washing up bowl? 5 litres, 10 litres?

A 3kw instantaneous water heater only delivers around 1 litre of hand
hot water per minute. So, it will take you 5-10 minutes to fill the
washing up bowl. Are you okay with that?

That's for water coming in at 5C, and washing up water at 50C.

If that be so, an irksome non-solution.

I think it may depend on what the (worst case) goal of the solution
needs to cover?

If it includes actually *needing* a bowl full of washing-up
temperature water several times a day than anything 'instant' is going
to have to be pretty powerful, as is any local water store, if not
either quite high capacity or high power (for reasonable recovery
time).

I've no idea how powerful our balanced flu combi-boiler-sized
multipoint water heater is but even that would take quite a time to
fill a basin with hot water (mainly the time taken to get the hot
water to the basin) and a fair time to fill even a corner bath, as
does the combi boiler in daughters flat (where you start the bath
running then go and do something else for a good time).

When having baths at Mums years ago with a big HW cylinder you could
run a bath pretty quickly (all be it only one without waiting ages).

And if you were suggesting filling a kettle with hot water from any
such hot water source, I'm not sure what advantage that would be other
than saving time?

There isn't anything much more efficient than a kettle (the element in
direct contact with what it's heating in a reasonably insulated
(plastic?) container) and so likely more efficient than heating and
storing the water to use later or from an instant heater (unless gas
because of the potentially cheaper energy costs).

If you are talking of washing crockery, depending on how much and how
heavy the soiling (baked on stuff that might appreciate being soaked),
I wonder if Jeff could test / vouch for how practical it might be to
wash a plate under the instant hand washer?

Cheers, T i m

Thanks Tim, very informative. Youve certainly added to our list of
needed considerations.
I like the "back to simplicity" kettle idea.
--

Mike

On Thu, 01 Apr 2021 10:00:07 +0100, Mike Halmarack
wrote:

snip

Thanks Tim, very informative.

You are more than welcome.

Youve certainly added to our list of
needed considerations.

I think it's one of those things that can sort of answer themselves,
when you get a feel for how much energy it takes to get water to the
temperature you need for your particular task.

I like the "back to simplicity" kettle idea.

And that (without us realising it possibly) can provide a fairly good
indicator of how much energy over what sort of time it's likely to
take any solution to get a known quantity of water up to the desired
temperature (or 'science' as it's called). ;-)

eg, Say you found you needed a whole 3kW / 2l kettle of water to make
enough washing up temperature water and that took 2 minutes to boil,
then it's likely to take any 3kW water heater around that time (likely
longer) to get that volume of water to that temperature.

Even the biggest / most powerful burner on the hob generally takes
quite a while to get 2l pot of water to the boil, especially if you
are watching it. ;-)

Cheers, T i m

On 01/04/2021 10:00, Mike Halmarack wrote:

Thanks Tim, very informative. Youve certainly added to our list of
needed considerations.
I like the "back to simplicity" kettle idea.


There is always the option of an induction hob too. Just
heat up a (non-electric) kettle on it, unless you already
have a gas hob which is just as fast. Failing that get
a 3Kw kettle before the EU ban them.

T i m wrote:
If it includes actually *needing* a bowl full of washing-up
temperature water several times a day than anything 'instant' is going
to have to be pretty powerful, as is any local water store, if not
either quite high capacity or high power (for reasonable recovery
time).

I was wondering about feeding an instant electric heater from a hot water
supply.

This might sound strange, but hot water supplies aren't always hot:
- there's the leg of cooler water before the hot water comes through
- in a tank system the boiler may not have run recently and the water be
lukewarm
- the storage temperature may be lower than you would want for washing
dishes

Is there any reason not to feed such a heater from say a 30-60C supply?

Theo

On 01 Apr 2021 16:40:56 +0100 (BST), Theo
wrote:

T i m wrote:
If it includes actually *needing* a bowl full of washing-up
temperature water several times a day than anything 'instant' is going
to have to be pretty powerful, as is any local water store, if not
either quite high capacity or high power (for reasonable recovery
time).

I was wondering about feeding an instant electric heater from a hot water
supply.

This might sound strange, but hot water supplies aren't always hot:
- there's the leg of cooler water before the hot water comes through
- in a tank system the boiler may not have run recently and the water be
lukewarm
- the storage temperature may be lower than you would want for washing
dishes

Is there any reason not to feed such a heater from say a 30-60C supply?

Coincidentally I have referenced such an idea elsewhere and belive
someone here is already (successfully) doing such a thing.

I set the temperature on our Multipoint to not be too hot (for hands)
when running at full temperature but there may be a slight conflict of
interest between the temp required at the basin and the sink (the sink
maybe wanting it hotter for heavy soiled crockery / cookware if we CBA
to use the dishwasher).

A mate has a very long house with the indirect HW tank in the middle
of the building and the main bathroom at one end. I'm guessing it
could be ~20m between the two and with those stupid 'waterfall' type
taps it takes *ages* [1] to get hot water at the basins especially if
it's not been used for a while.

Cheers, T i m

[1] Longer than I would tolerate if I had his space / money. Given
it's low pressure, a tiny direct HW cylinder with immersion in series
with the hot feed in a cupboard nearer the bathroom would be what I
would do.

The other two bathrooms are nearer the HW cylinder and he has Quooker
taps in the kitchen and utility room. ;-)

On 01/04/2021 09:36, T i m wrote:

If you are talking of washing crockery, depending on how much and how
heavy the soiling (baked on stuff that might appreciate being soaked),
I wonder if Jeff could test / vouch for how practical it might be to
wash a plate under the instant hand washer?

Funnily enough I'd been thinking about that myself. I am sure it would
work very well - I never use a bowl for washing up anyway, just a thin
stream of hot water from the kitchen sink tap and a sponge/scourer pad
with some washing-up liquid on it. The extra force of the instant-heater
spray should shift food residue on the plate far more efficiently than
the stream of water I use. In any case, isn't that how dishwashers work
- by spraying hot water onto the soiled crockery, pans, and cutlery?

On a somewhat unrelated, or perhaps related, matter the problem of hard
water was raised earlier. Does anyone know why the heated parts don't
seem to suffer much from furring up, but spray heads and shower heads
do. Is it just that when they are switched off the calcium and magnesium
salts in the water are deposited when the water evaporates?

--

Jeff

On Thu, 1 Apr 2021 19:19:38 +0100, Jeff Layman
wrote:

On 01/04/2021 09:36, T i m wrote:

If you are talking of washing crockery, depending on how much and how
heavy the soiling (baked on stuff that might appreciate being soaked),
I wonder if Jeff could test / vouch for how practical it might be to
wash a plate under the instant hand washer?

Funnily enough I'd been thinking about that myself. I am sure it would
work very well - I never use a bowl for washing up anyway, just a thin
stream of hot water from the kitchen sink tap and a sponge/scourer pad
with some washing-up liquid on it.

Step daughter was fairly obsessed about rinsing any soap off her
washing up and so would tend to use even more heat / water.

The extra force of the instant-heater
spray should shift food residue on the plate far more efficiently than
the stream of water I use.

Agreed.

In any case, isn't that how dishwashers work
- by spraying hot water onto the soiled crockery, pans, and cutlery?

It is indeed ... and possibly hotter water than we might want to
plunge our hands into, even with gloves?

On a somewhat unrelated, or perhaps related, matter the problem of hard
water was raised earlier. Does anyone know why the heated parts don't
seem to suffer much from furring up, but spray heads and shower heads
do. Is it just that when they are switched off the calcium and magnesium
salts in the water are deposited when the water evaporates?

Good question but whilst you can get furring around the spout of a
kettle, you do also / more_often get it around the element?

Cheers, T i m

On 01/04/2021 19:19, Jeff Layman wrote:
The extra force of the instant-heater spray should shift food residue on
the plate far more efficiently than the stream of water I use. In any
case, isn't that how dishwashers work - by spraying hot water onto the
soiled crockery, pans, and cutlery?

get a dog. Polished clean plates which are then easy to 'wash'

On 31/03/2021 16:17, Mike Halmarack wrote:

I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?

Sadia heaters were the usual choice in the past, which usually were over
the sink with a long spout that dripped as the water heated up in the
tank and expanded - the tap was on the inlet. I stayed at a place where
the tank was under the sink and the hot tap knob was connected via a rod
through the tap to the inlet tap underneath - it just looked like a
normal hot tap.

--
Max Demian

On 31/03/2021 16:17, Mike Halmarack wrote:
I'm seeking some advice on choice of electric, undersink boiler.
I only have a need for hot water, Maybe 4 washing up bowls a day, 8
washhand basins full per day ( unless the water from the boiler is
drinkable and then 8 kettles full per day too).
Can anyone recommend a small undersink boiler that will be suitable
for this?
Also, would the smaller type of electric boilers have a plug-in rather
than a hard wired option?

If fitted to a cold water supply you will need a non-return valve,
pressure relief valve and an expansion vessel (though a length of pipe
is allowed for some heaters in lieu of an expansion vessel).

As I had a water supply from a hot water tank it meant I didn't need any
of these protection devices.

At the time my hot water tank was badly lagged and heated by electric
only and I had a shower, so I only turned the immersion on if necessary.