Dead simple plumbing/hot water question

[Andy Hall]

Let's be honest. It does here, doesn't it.

[Doctor Drivel]

Matt? Your Little Middle Englandness is getting the better of you.

[Dave Plowman (News)]

Well, I asked where you'd buy a suitable tap of the type the OP has and all you came up with was Screwfix basic stuff. Hardly a substitute.

'Makita's' what?

[Doctor Drivel]

Will you please eff off as you are plantpot.

[John]

OP here:

Thanks for all the posts about how to improve flow-through in my kitchen HW tap. I didn't realize (and certainly was never told by MFI!) that my fancy tap should really be pressurised! I will be looking at the pump suggested by a couple of posters, and also at the cheaper alternatives suggested.

Just for info: I'd thought about increasing the diameter of the feed-pipe to 22mm because I was thinking in terms of weight of water coming to the tap. What I hadn't considered - as several pointed out - was that this would increase the amount of cold water waiting to be run off, before the hot finally came through! duhhh.

Thanks a lot everyone -- very useful exchange, for me.

John

[Doctor Drivel]

If it is a spray attachment tap then they usually need 1.5 bar to operate the spray. This means a pump is around 2 bar minimum, which is usually an expensive pump. A shower pump will not do, as they are designed for continuous running for 15 to 30 mins 3 to 4 times a day. A kitchen tap may be turned on for a few seconds then off then on again. This may lead to early failure on a pump not designed for this operation.

Personally I would abandon the taps and get a non-spray attachment high or low pressure mixer.

That will not make the tap work properly.

[Dave Plowman (News)]

Not pressurised as such but designed for mains pressure water which is at a higher pressure than most storage systems.

And it is annoying that tap makers don't see fit to label them with the pressure required. Probably because they're in the main made in Italy where such refinements as stored water systems aren't common.

[Dave Plowman (News)]

The same cost as a decent mixer?

You don't have to look too far to find a suitable one. Surprising given your extensive use of Google.

Personally I would abandon the taps and get a non-spray attachment high

Well yes. You would. Make a problem go away by the easiest method *you* understand.

It would also likely cost more than a pump...

[Doctor Drivel]

Will you please eff off as you are a complete plantpot.

[Doctor Drivel]

Or plantpots don't know the difference between high and low pressure taps and fit pumps.

[Dave Plowman (News)]

Not that I expect an answer, but just how do you tell the difference? I'll give others the answer - you can't. A 15mm connector is no guarantee it is a low pressure type.

It constantly amazes me just how little practical experience you have for one who claims so much...

[Dave Baker]

Which might have some merit if the pressure created by a head of water was actually affected by the pipe diameter - which it isn't.

What I hadn't considered - as several pointed out -

-- Dave Baker Puma Race Engines

Camp USA engineer minces about for high performance specialist (4,4,7)

[Ron Lowe]

That's correct for a static head. However, under flowing conditions, the pressure drop over the length of pipe will be less with the larger pipe.

( At the cost of a larger volume to be flushed befor the hot arrives. )

Not that it makes the slightest difference in this case.. the pressure drop in the pipe is insignificant compared to the pressure difference between a ( say ) 3 Bar pressurised system required here and a fractional bar gravity fed system which is what we have. Even replacing it with the fattest, most directly-routed pipe imaginable can still only bring the flowing pressure closer to the static head, which itself is still way to small.

[Doctor Drivel]

Will you kindly eff off as you are a total idiot.