Under sink instant ...
 

  You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more

Under sink instant heaters for my bathroom

16 Posts
12 Users
0 Reactions
214 Views
Posts: 4324
Full Member
Topic starter
 

The pipes from my boiler to bathroom are about a mile long as far as I can tell and the water takes 2 days to get there from the boiler. OK it takes a long time, it feels like 2 minutes but having never timed it it’s probably not actually that long.

But it means we never get hot water at the sink, what mostly happens is we just use cold (fine in the summer, not fine this morning) or heat up a lot of water that never makes it out of the pipe.

I’m considering fitting an under sink instant heater - does this seem like a sensible idea? How powerful will I need to get a decent flow?

I know I’ll have to get a new feed put in from the consumer unit.

This kind of thing https://www.screwfix.com/p/triton-instaflow-multi-point-undersink-water-heater-10-1kw/588hpB


 
Posted : 20/11/2022 11:39 am
Posts: 1318
Full Member
 

We have one it’s OK can’t have a high flow as it’s won’t heat up enough. Ok for washing face


 
Posted : 20/11/2022 1:18 pm
Posts: 6978
Free Member
 

with no central heating/boiler, all our hot water is electric.
look at Stiebel Eltron
https://www.stiebel-eltron.co.uk/en/products-solutions/dhw/instantaneous_waterheater/all-products.html


 
Posted : 20/11/2022 1:21 pm
Posts: 4324
Full Member
Topic starter
 

We have one it’s OK can’t have a high flow as it’s won’t heat up enough. Ok for washing face

what power do you have? I assume they’ll be like an electric shower, in that some lower output ones are awful.

I’ll be happy if I can fill a sink up with hot water or wash my hands tbh.

look at Stiebel Eltron

Cheers 👍


 
Posted : 20/11/2022 4:44 pm
Posts: 15068
Full Member
 

Might be more worth upgraging the boiler in the long run if it's an ancient one?


 
Posted : 20/11/2022 5:12 pm
Posts: 13916
Free Member
 

Might be more worth upgraging the boiler in the long run if it’s an ancient one?

That's not going to change the time of takes the hot water to reach the to though.

OP: I have one in my office that feeds the kitchen sink and the bacon in the toilet.
I think it's a Zip and has a 3 or 5L tank* with thermostat that it heats up so there's no waiting.
Just plugs into a socket and I have it in a timer.

* That's not instantaneous though is it! 🤦🏻‍♂️


 
Posted : 20/11/2022 7:56 pm
Posts: 1243
Full Member
 

I have one in my office that feeds the kitchen sink and the bacon in the toilet

Took me 3 goes to work out what that's an auto correct for (basin, obviously innit)


 
Posted : 20/11/2022 8:04 pm
Posts: 4324
Full Member
Topic starter
 

Might be more worth upgraging the boiler in the long run if it’s an ancient one?

Yeah boiler's fine, it's just a long run to the bathroom - it runs along the ground floor, past the bathroom and up the wall, then has to go back on itself to get there. Not really an issue for the shower, just takes a while to get hot. But for the basin tap the boiler probably fires multiple times without the hot ever reaching the tap. We're getting better and not running the hot, but it would be nice to be able to 🙂

OP: I have one in my office that feeds the kitchen sink and the bacon in the toilet.
I think it’s a Zip and has a 3 or 5L tank* with thermostat that it heats up so there’s no waiting.
Just plugs into a socket and I have it in a timer.

They are an easier solution electrically as, like you say, it could just be plugged in. But not ideal for our intermittent use, we'd constantly be heating water up that doesn't get used.


 
Posted : 20/11/2022 8:07 pm
Posts: 15068
Full Member
 

How long is a long time?

What sort of boiler system do you have?

How old is it?

Do you live in Windsor castle?


 
Posted : 20/11/2022 8:17 pm
Posts: 4324
Full Member
Topic starter
 

How long is a long time?

Seeing as you asked I just went and timed it. 67 seconds.

What sort of boiler system do you have?

Worcester Bosch combi

How old is it?

2004.

Do you live in Windsor castle?

No.

But it's a relatively long thin house and the route from downstairs to upstairs for the water is about 10 metres, the 5 back again to the tap plus 3 metres up the wall from under the floor.

The age and type of boiler is irrelevant in this case (apart from the fact that the original HW tank was much closer to the bathroom, but that ship sailed long before we bought the house). I've just remembered as well that it was even worse before we redid the bathroom, it used to loop up over the ceiling too!


 
Posted : 20/11/2022 8:36 pm
Posts: 0
Free Member
 

I have come across this problem a few times before. Quite often if a combi is fitted to existing hot water systems and the old hot pipes are 22mm or sometimes 28mm with long runs, this is what happens. The 15mm hot from the combi has to push hot water through the cold water in the bigger pipes and it doesn't push all the cold water to the tap like you'd think it would, it just mixes in the pipe. Upgrade all hot pipes to 15mm and I guarantee it will work perfectly.


 
Posted : 21/11/2022 9:17 am
Posts: 11486
Full Member
 

Completely random idea and possibly stupid...taken from vehicles/boats/coaches that heat water from the engine coolant to provide hot water/wet heating.

Fit a small insulated calorifier in the bathroom, and replumb the hot tap into it. Divert the central heating through the calorifier to heat it, or you could try diverting the shower hot feed through it but I'm not sure if that would result in a lukewarm shower for the first 15 minutes, depends how efficient they are.#

(Obv a calorifier is basically a small hot water tank so perhaps I'm simply saying refit a small (unvented?) hot water tank in the bathroom!)


 
Posted : 21/11/2022 9:50 am
Posts: 2095
Full Member
 

is running a dedicated 15mm pipe an option?

I know in hotels there’s a system you can get where the hot taps are all on a flow and return circuit with hot water being pumped around constantly (tho probably on a timer in a domestic setup) but not sure that would work with a combi


 
Posted : 21/11/2022 11:38 am
Posts: 16025
Free Member
 

Does your boiler have a preheat function?


 
Posted : 21/11/2022 1:17 pm
 irc
Posts: 5188
Free Member
 

As far as heating up water that never gets there goes. Gas is a third the price of electricity so even if 2/3rds if the water the boiler heats ends up sitting in the pipes you break even.The heat from the pipes will leak into the house so it isn't actually lost unless perhaps under the ground floor in the void.


 
Posted : 21/11/2022 1:23 pm
Posts: 13916
Free Member
 

Took me 3 goes to work out what that’s an auto correct for (basin, obviously innit)

FFS!!!
🙂

They are an easier solution electrically as, like you say, it could just be plugged in. But not ideal for our intermittent use, we’d constantly be heating water up that doesn’t get used.

When do you need it generally? Mine is on a timer so comes on 30 mins before it's going to be needed, so you could limit when it's actually on.
Also don't forget that you're using power to heat the water with the boiler anyway!

(We have the same issue - it takes about 45 seconds for the hot water to reach the tap/shower in our en suite. We've just lived with it for 20 years!)


 
Posted : 21/11/2022 1:37 pm
Posts: 356
Full Member
 

I've got an Ariston slim under sink unit for ho****er in the bathroom. It works great; was a doddle to install - The electrician had to run a new 10mm T+E cable for it; and he also needed to get the electric co to send someone to check the master fuse rating was high enough (as you're adding an extra 30A circuit to your fuse board)

It's quiet and heats up quickly.


 
Posted : 21/11/2022 4:59 pm

6 DAYS LEFT
We are currently at 95% of our target!