Hi, we have just moved home and have discovered that the hot water seems temperamental at best! If you run the water slowly then it heats up. If you run the water fast then it turns cold. This is a nightmare when we want to run a bath! We have a combi boiler which works OK for the heating! Any help would be great.

Hi Bluesmartie83 and welcome, is this just an issue in the bath? Or is it at all fixtures?

Yes the previous owner just said he didn't take baths and left the water to run slowly to get a sink full downstairs!

Do you have Tankless Hot water heater in your new house ?

Back to you

Milo

Yes no water tank.

With presence of Tankless Hot Water heater, the symptoms you describe are most-likely related to undersized gas pipe going to the water heater. If demand for hot water is high, and there is not enough gas going to the heater, heater will slow down water flow though the heater, in attempt to produce hot water as set on the thermostat.

Look at your tankless water heater. See how far it is from the gas meter, and if possible, see how big gas pipe goes from gas meter to the tankless. Let me know these two values

Back to you

Milo