Low hot water pressure

[Botch]

Have just fitted a new bath with mixer taps and shower wand. The hot water pressure is almost non-existent, and water just trickles out too slowly to fill bath. Old bath and taps were fine.
Plumber suggested that the bore of "modern new-fangled" taps was too narrow for bath use and restricted the pressure. Could that be correct? Any solution?
Can't replace taps, since holes drilled inexpensive bath and won't find others to fit.
Would a pump on the hot system be the answer (ie: Stuart Turner Monsoon negative/single/2 bar, model?). Cold mains pressure is OK.
The bath is fitted upstairs in a converted bungalow, and the hot water cylinder is on same floor level. Base of cold storage tank only a couple of feet above top of tap, so pressure would be expected to be low, but it was OK before.
Did notice slight drop in pressure when plumber replaced old hot water cylinder with new one a month ago, but called him out again and he disconnected pipework just before bath connection to prove the flow was acceptable, which it was. He blamed taps, saying the 22m pipe is in effect reduced to about 12mm inside the tap, and this was the problem.
Gravity central heating, NOT a combi boiler.
Help!!!!!!!

 

[Softus]

Could that be correct?

Could be. And is.

Any solution?
Can't replace taps, since holes drilled inexpensive bath and won't find others to fit.

Your options are:
1. Replace bath and taps.
2. Replace cylinder with an unvented one.
3. Fit a pump.

Would a pump on the hot system be the answer

Yes.

(ie: Stuart Turner Monsoon negative/single/2 bar, model?).

Why do you suggest a negative head model?

The bath is fitted upstairs in a converted bungalow, and the hot water cylinder is on same floor level.

Fit an Essex flange to feed the pump.

Base of cold storage tank only a couple of feet above top of tap, so pressure would be expected to be low

Still enough for a positive head pump.

...but it was OK before.

Do you mean 'before' you got the new-fangled taps?

Did notice slight drop in pressure when plumber replaced old hot water cylinder with new one a month ago, but called him out again and he disconnected pipework just before bath connection to prove the flow was acceptable, which it was. He blamed taps, saying the 22m pipe is in effect reduced to about 12mm inside the tap, and this was the problem.

His analysis is correct. His advice should have been sought before drilling the holes in the bath.