Low hot water pressure?

My tenants are having problems with their hot water and I cannot figure out what the problem is! Hoping someone here can help... The flat has a Pulsacoil heater, I think it must be an original one as it doesn't say anything else on it. It also doesn't have any display visible as far as I can tell.

They are reporting that the hot water at the tap is only tepid, and that the pressure from the hot taps is very low, although the pressure is fine from the cold tap. I spoke to someone at Gledhill who quoted £340 for an all costs included call out / repair, but they felt that the low water pressure was unlikely to be caused by the Pulsacoil so I'm obviously loathe to pay that amount.

Because its only the hot water that's affected it seems logical to me that it must be something to do with the feed in/ out of the Pulsacoil rather than the mains supply - any suggestions on what I could do to fix it?

Thanks in advance
Rayne

Well not much to go on!
What unit is it?
If a PC 2000 then it could be the Y type filter blocked.
Or the PHE scaled up
Mike

It's an original Pulsacoil as far as I can tell - looks a lot like this one: forums.moneysavingexpert. com/showthread.php?t=1283451 (had to post with a space in the middle as new members aren't allowed to post external links! Sorry!)

Had a plumber round today who thought the economy 7 timer wasn't powering the immersion, but that wouldn't explain the low hot water pressure? Other thought was whether the blender valve could have gone too? Not really sure what else could cause low pressure...

Well if you have a mixer / blender valve and it is a PC III ?
Then the internal coil could be scaled up

Hmm ok.. Is that the heat exchanger?

Not being rude.
How long have you rented this house out?
If it is a PC 2000 then it will have a PHE.
If it is a PC III then again a PHE.
A BM II internal.
Go on Gledhill website.
Download the manuals until you find yours, that will be a great help.
Sounds like you need a Gledhill guy out.
Google up for 1 in your area.
Again for the 100th time if when posting your perils, by putting location someone may offer more help.

Appreciate your efforts to help and that you're not trying to be rude. I'm not a 'professional' landlord, it was previously my own flat and i'm renting it out until we're able to sell. So I'm afraid while I like to think I'm better than many at technical stuff I'm by no means an expert...
I'll call Gledhill again in the morning.
Thanks.