low hot water pressure - appropriate kitchen tap

NickNickleby · 04-04-2023 2:30pm #1

Greetings all !!

Son needs new kitchen tap. Monobloc, but after that, all that matters is that it looks nice and is expensive (to my mind). However, while the direct from the mains cold feed is fine, the hot is dreadful. (I know for a fact that my own isn't great, and I measured it - 20 seconds for a litre , 5L per minute. His is much worse, a guess would be about 50-60% of my feed.) His kitchen was extended and the sink moved about 20 feet away from where it was. The original pipes are not visible, but behind the new sink, the pipes are 1/2" copper. His existing tap is monobloc mixer tap with the braided tails. I assume the bore of these tails is about 5 or 6mm. Presumably this goes some way to explaining the poor pressure from the hot. Anyway, all the preceding is for context, now to the question.

If a mixer tap specification says its suitable for 0.3Bar to 5Bar, why would it also say "not suitable for gravity fed systems"? My understanding is that for gravity systems the pressure will be about 0.1Bar per metre height. So we're probably expecting about 0.5 to 0.6 Bar on the hot feed. What's the risk of using such a tap?

For further clarity, here's a link to the preferred (mad expensive, Ted) tap:

https://www.screwfix.ie/p/franke-lina-kitchen-tap-chrome/325PY?gclid=Cj0KCQjwla-hBhD7ARIsAM9tQKtywYu4Gm9VrsGBmssA0rQP2vTET-0kRE71G1Zd_uzEPfug1YUnP2oaAl_BEALw_wcB&gclsrc=aw.ds

I appreciate any comments. And I'm not too proud to have any of my wild assumptions debunked publicly. 🤣

Thanks!

serox_21 · 04-04-2023 3:09pm

from screwfix website:

Gravity Fed Systems - Not Suitable for Gravity-Fed Systems

if your hot water is coming from hot water tank that's fed from cold storage tank then tap water pressure will be as you describe.

Change the tap and buy one that's suitable for Gravity-Fed Systems.

NickNickleby · 04-04-2023 3:18pm

https://www.boards.ie/discussion/comment/120439952#Comment_120439952

Thanks for the comment.

Yep, I saw that, which is what led to the question - "what's the risk?" . Bearing in mind the low operating pressure requirement of this specific tap.

My thinking is that gravity fed - lower pressure. So, if my cold tank (feeding the hot tap via the hot tank) is for argument's sake able to supply 0.3 bar, why is the quoted tap not suitable for gravity fed system? Insisting on gravity-fed suitable taps is very limiting, which is why I'm trying to get a handle on this.

To me, the worst case scenario is that the cold feed could over come the gravity fed hot feed and send the water up through the hot tap and potentially overflow the tank in the attic (hopefully the overflow pipe would save the house from destruction). So, if THAT's a real risk and not just my fevered imagination doing its worst, then yes I understand the nature of the risk. But the 0.3Bar min spec is still niggling me...... that's me hoping it's a 'get out of jail free' card.

theteal · 04-04-2023 3:20pm

These thingies any use???

https://www.screwfix.com/p/salamander-pumps-tapboost-booster-single-outlet-booster-0-5bar/590JF?kpid=590JF&ds_rl=1241687&ds_rl=1245250&ds_rl=1245725&ds_rl=1245250&gclid=Cj0KCQjwla-hBhD7ARIsAM9tQKtSFBWQBzsjDBM9SHm_6saneJaqTDgNGubDzG3flQJKEPt38XBMSlAaAmb_EALw_wcB&gclsrc=aw.ds

10-10-20 · 04-04-2023 4:10pm

I think it's that you don't get the intended flow by way of an aeration valve or fancy spray head pattern as some of these require more flow before the features such as aeration become established. I think that's all really - cosmetic in all or most cases.

NickNickleby · 04-04-2023 5:41pm

https://www.boards.ie/discussion/comment/120440001#Comment_120440001

I was looking at that as well, but its quite dear. I suppose, thinking about what 10-10-20 says below, if nothing else it will ensure the aerator/spray functions properly. Probably won't be any good without it.

Thanks for your response.

NickNickleby · 04-04-2023 5:45pm

https://www.boards.ie/discussion/comment/120440184#Comment_120440184

I think they (son and his wife) think they'll have a restaurant style sink if they get this tap installed. So, I think the tap AND the pump are probably the way to go - I'm in shock at the total cost of doing this, even though its not my money !!

Thanks for your response.

10-10-20 · 04-04-2023 7:26pm

I remember looking at replacing mine with a similar model after the valve went - North of 600 EUR for the same monoblock!

Got a valve in the end for 32 EUR and it's still there 10 years later.

low hot water pressure - appropriate kitchen tap

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