Search the forum,

Discuss Thinking about a 10mm hot tap feed in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Status
Not open for further replies.
Messages
9
Hi. My boiler is about 20 feet away from the kitchen taps. The water to the sink hot tap takes quite a long time to get really hot. The current feed to all taps in the house is 15mm pipe; I'm thinking of running a length of 10mm pipe from the boiler to the kitchen hot tap so that less volume of water has to be shifted through the pipe. The dishwasher, and all other taps would stay on the 15mm feed. What are your thoughts on this idea?
 
Sounds feasible.

You don't know the existing run of the hot water pipe do you?

It may be a lot longer then the 20 feet you estimated.
 
What Type of Hot water system is this?
Combi?
Open vented or unvented Cylinder?
Multipoint?

Excuse my asking but people do call all sorts of things 'Boilers'.
 
Sounds feasible.

You don't know the existing run of the hot water pipe do you?

It may be a lot longer then the 20 feet you estimated.

I know the run intimately as I installed it :)

Anyway, what about my idea? Would the narrow pipe cause an unacceptable resistance to the flow?
 
Should be fine
 
It should be ok.
Only thing I can think is it may be slightly noisy
( possibly)

I would find out why it takes so long first though.

Some taps appear to have a powerful delivery but when measured they can be quite low ( litres per min).
 
Last edited:
This is what im thinking of doing. Boiler is in the garage and the kitchen is at the furthest point away, luckily to get to the bathroom it goes through the wall and up into the bathroom.

I was hoping to use 10mm for the kitchen run to reduce the amount of time it takes, after all flow isnt as important to fill a sink.
 
Bad idea 10mm would be the minimum
 
Last Plumber: "I would find out why it takes so long first though."

I would guess something like three litres of water have to be shifted and then there's the normal boiler heat-up time.

From a cold start probably about 90 seconds before the water is usefully hot.

This boiler has a 'Comfort' setting that claims to keep DHW hot and ready. I haven't used this setting yet but will give it a try. Do you know if 'Comfort' setting is going to be expensive to run?
Mind you, I'd still have the problem of shifting a load of cold water before the hot came through to the tap.
 
Last Plumber: "I would find out why it takes so long first though."

I would guess something like three litres of water have to be shifted and then there's the normal boiler heat-up time.

From a cold start probably about 90 seconds before the water is usefully hot.

This boiler has a 'Comfort' setting that claims to keep DHW hot and ready. I haven't used this setting yet but will give it a try. Do you know if 'Comfort' setting is going to be expensive to run?
Mind you, I'd still have the problem of shifting a load of cold water before the hot came through to the tap.


Comfort normally preheats primary water in some way. Depends on boiler. What is the flow rate on the hot water tap and on water main?
What is the pressure on the main?
 
I would guess something like three litres of water have to be shifted and then there's the normal boiler heat-up time.

15mm tube is about 0.14 litre/m so 20 ft, or 6m, contains about one litre of water. A kitchen tap delivers about 4 litre/min so about 15 seconds of your 90 seconds delay is attributable to the volume standing in the pipe. Replacing the pipe with 10mm is not going to cure the problem.

Enable HW pre-heating on the boiler. This should reduce the time delay down significantly. Another solution to this problem is to install a small 'instant' water heater under the sink. About two hundred notes will cover it. Pre-heated HW does waste a small amount of gas but you can buy quite a lot of gas for ÂŁ200 so I'd try this first.
 
Chuck: That's all very good information; thanks.
This morning I did a quick test and found that it actually took 40 seconds to get decent hot water and that used 6ltr of water. Doesn't sound very long does it, but it does waste a lot of water. The central heating was already hot so that may have sped things up. I'll try the boiler Comfort setting and see what difference that makes.
 
Comfort normally preheats primary water in some way. Depends on boiler. What is the flow rate on the hot water tap and on water main?
What is the pressure on the main?
The hot tap has a healthy flow. I don't have a guage to measure water pressure but it seems very good.
 
You could have a go by displacement. If you have a long straight run? Crimp the end of a length of 10 mm copper pipe thread it down the 15 mm cut and crimp end reconnect 15 mm. Then give it a try against existing findings.
 
If you know the system in detail and are more concerned about the waste of water than time, you'll probably be able to work out whether this might work on your system:

Hot water without the waste with CombiSmart

My understanding is that they can be adjusted so the minimum flow setting can be set to suit your boiler, but worth checking with manufacturer. I think Veissmanns have a very low minimum flow, so this gadget might suit you? Not fitted one myself though.
 
Status
Not open for further replies.

Reply to Thinking about a 10mm hot tap feed in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Creating content since 2001. Untold Media.

OFFICIAL SPONSORS

OFFICIAL SPONSORS

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock