I'm after a bit of advice Please. I an selling my mothers house and the seller has had a plumber round to check everything out. For info the house had a new combi boiler installed last year, replacing a conventional one.
The report has stated the the hot water temp for the kitchen tap (boiler is in there) and the bathroom tap are both 50DegC but the bath tap is only 40DegC. the bathroom tap is a mixer one but has 2 seperate levers for hot and cold.
Not sure I understand what you are referring to as the "bathroom tap" as distinct from the "bath tap".
Is it possible that the 40 degree one could be a thermostatic mixer tap which limits the output temperature by automatically mixing cold with the hot (as used in hospitals and disabled facilities)?
Is the combi's output temperature adjustable? Even 50 degrees is not very hot for swilling greasy dishes!
Assuming the combi doesn't regulate the HW temperature the temperature will be inversely proportional to flow so if the flow rate from the bath tap is higher than from the basin and sink then the water will be cooler coming out.
It's how it works, not a fault: you can pay extra for boilers which regulate HW temp, or not. I chose not in my house as all outlets have mixers so you can get the temp you want, and if you want to top up the bath or fill a pan for cooking you can run hot water slowly so it's piping. When I did have a non-mixer tap on a basin I fitted a cheap thermostatic mixing valve so the hot tap wasn't scalding.
The bath tap can probably draw water fast enough that the boiler is unable to heat it as much as with the slower taps. Turn down the rate of delivery on the bath tap to match that produced by the basin, and it will deliver at the same temperature.
This is normal behaviour on most combis (and probably the one that helps perpetuate the myth that combis can only deliver tepid water - when its actually users just not understanding (or wilfully ignoring) the limitations).
Alternatively, if you're in Scotland and it's a recent fitment, there may be a temperature regulating mixer valve under the bath to prevent scalding. It's not a requirement for basins.
Legally, houses are sold 'as is' and buyer beware (mostly).
Although the potential buyer has sent a plumber round, you have no obligation to fix any 'faults' that he might find. Suppose he'd sent an electrician around who amazingly found you needed a rewire as the house isn't 'up to current standards'.
This might be a way of negotiating a lower price.
You can tell the buyer to take a hike, or knock £50 off the price because of the 'problem', or have it fixed at your expense.
On one combi model for which I have some detailed knowledge (Vokera Excell 80SP) the CW inlet valve acts as a settable flow restrictor, as well as being an isolator for maintenance. The maximum opening of said valve is supposed to be set and locked during installation to set the flow rate to the most 'open' draw-off point, and hence avoid the problem of excessive flow and low outlet temperature. Of course this assumes that the mains inlet water pressure and temperature remain reasonably constant, so it's not perfect, but in practice is much better than nothing.
On a friend's installation there were complaints of low bath and shower temperatures and I found that the inlet valve was set fully-open, 'as-delivered'. The lazy original installer had never bothered to set it, despite full details being in the commissioning instructions. (Nor had he set the pot that controls the maximum power o/p to the CH circuit!)
So, to the OP (or his buyer), a simple adjustment might be all that's needed.
We're having a combi fitted next month, to replace the current Rayburn+back boiler setup. Will it be absolutely necessary to fit a temp regulating valve for the bathtub? (Yes, this is in Scotland.)
Only if you're fitting a new bath and/or taps I think. We had to because it was a new bathroom.
Can't imagine why you'd want a combi though. ;-) I did a 16 mile run yesterday with a friend who confessed that she was going home to a house with no hot water due to a PCB failure in her combi. No HW tank, no immersion. I enjoyed a lovely soak in my bath. ;-)
No new bath. Next year, when the bank account has recovered from the new boiler, we hope to install a shower room.
The existing bath has an electric shower over it; the washing machine and dishwasher heat their own water; we have a working fireplace - and getting rid of the cylinder and storage tanks will free up storage space in this rather small house. I hope we don't regret it next winter...
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