New Kitchen Mixer Tap

[caveman2]

I have an old 35 year old Franke 2 bowl sink and mixer tap. The tap needs replacing but I need assurance that the new one will fit. The old tap has a 30mm threaded column to which the H&C feeds are sweated into it. The whole assembly is then fixed with a 40mm brass nut.
Will a modern mixer tap fit exactly into the hole in the sink or will it be too big or small because of a change to metric sizes etc.

 

[blup]

You can get reducer washers

Blup

 

[oldbuffer]

1. The standard tap hole size is 35mm, and has been for many years.
2. Provided the tap you buy has a base diameter (above the sink) of 40 mm or more you should be OK.
3. The only way of being absolutely certain is to remove the existing tap and measure the hole. However, given the shank diameter of the existing tap is 30 mm, and the nut 40 mm, I would consider this probably unnecessary.
4. The replacement is unlikely to have sweated in pipework. More likely to come with flexible hoses and a "horseshoe" washer to a fixing stud.

 

[caveman2]

Thanks both of you. I appreciate the new tap will have flexi-hoses, I only mentioned the fixed pipework to explain the type of assembly. Removing the nut is going to be a "joy" with little space to work with and having no box spanner that size.

 

[johnny2007]

Buy a box spanner, you won't regret it.
Never had a problem returning anything to screwfix... just saying...

 

[Harry Bloomfield]

You do need to ensure the tap you purchase, is suitable for your water pressure. Low pressure for an open vented system, high pressure for a combi heated system, of mains pressurised system.

 

[caveman2]

What isolator valves would you recommend fitting under my sink. Peglar isolator valves with screw, the same with small plastic lever or the larger Peglar ball valve?

 

[oldbuffer]

1. Pegler lever or butterfly valves. Doesn't matter which, a space issue really.
2. Your cold will (should be?) at mains pressure, so doesn't need to be full bore.
3. If the hot is off a combi boiler or an unvented hot water cylinder, again would not need to be full bore.
4. If hot is off a traditional hot water cylinder, you might consider full bore to avoid restriction.
5. However, the bore of the flexis is generally pretty narrow, so not point fitting full bore just in front of a restriction.
6. Depending on what flexi's you get, you might need two adaptors. Assuming 15 mm pipework and 1/2" BSP female ands to the flexis, look at Screwfix item 2665R. You can get isolation valves with flat faces, but so far as I know Pegler don't do them.

Incidentally, you will probably need to cut the existing copper pipes at the narrower diameter where they enter the old tap. Otherwise it may be very difficult to get the tap out.

 

[caveman2]

Sorry to resurrect this thread.
I am replacing my Franke mixer with another (35 years apart) but. The recommendations are for minimum .5 Bar. How do I know if I fulfil that criterion. I have mains cold and gravity fed hot from a copper cylinder in the storey above (bedroom) and the cold water storage tank in the loft.

 

[oldbuffer]

1. Pressure of hot at the kitchen tap can be worked out as follows (all in metres):
a. Height of kitchen, floor to ceiling.
b. Height of first floor (floor to ceiling)
c. Average thickness of ceilings (ground to first and first to loft). Probably around 0.125 metres each
d. Height of base of cold water storage cistern above joists in loft. (Probably effectively zero)
e. Height of highest point of tap spout above kitchen floor.
2. Pressure (in bar) = ((a + b + 2c +d)-e)/10
3. Typically ((2.4 + 2.4 + 0.25 + 0)-1.3)/10 = 0.375 bar

 

[caveman2]

Thanks OB. Those calculations are spot on for my house. Therefor with only .375 and not the minimum .5, I cannot use that tap. Is the only solution, to find one without those restrictions and why are they imposed on that tap and others that I've seen with a similar .5 bar minimum specified?
Needles to say, I don't want to be raising the tank in the loft just for a kitchen tap and why did my existing tap work perfectly?

 

[Harry Bloomfield]

Sorry to resurrect this thread.
I am replacing my Franke mixer with another (35 years apart) but. The recommendations are for minimum .5 Bar. How do I know if I fulfil that criterion. I have mains cold and gravity fed hot from a copper cylinder in the storey above (bedroom) and the cold water storage tank in the loft.

Gravity fed, will meet that 0.5bar minimum pressure.