correct pressure and dhw temp query

[BobbyJoe]

Hi everyone just checking if this is right regarding water pressure and combi boiler pressure:

Do hot and cold water always vary in pressure such as the following?
Cold water from tap filled 1 litre jug in 2 seconds
Hot water from tap filled 1 litre jug in 5 seconds

Gas combi boiler pressure is at 1.5 bar on (Vokera Easi heat plus) is this right for a top floor flat (3rd floor in a block of 6) and reckon the flat is around 10 to 12 metres high from the ground up.

Should the combi boiler DHW be set at a specific temperature it goes from 37c to 60c on the dial but I can't tell the temp as their are no numbers just 10 dots on the dial (no chance of legionella if there is not tank correct?) or does it not matter since water in building is mains fed both hot and cold feeds.

• Pressure reducing valve is fitted in the attic set at 1.5 bar this is for all mains fed water to the bathroom, bathtub, basin and shower.
• But there is no PRV in the kitchen for the kitchen sink/drinking water.
• I have single lever mixer taps in kitchen, bathroom and thermostatic mixer shower if this helps.

Thank you and as always I would appreciate your advice

 

[Chuck]

12 litre/s for hot water from a tap is correct for your boiler.

30 litre/s for cold water from a tap is very high. Presumably this is the kitchen tap so it's not impeded by the PRV.

The pressure gauge on the boiler reads the pressure in the central heating circuit. It is not relevant to the flow from taps in the building.

For best fuel economy, set the DHW to the lowest temperature that you find satisfactory. If the boiler is mains-fed and there is no DHW store legionella is not an issue.

 

[BobbyJoe]

Thank you for the reply, all the cold water outlets are high in pressure the kitchen and bathroom as well, I thought it might have to do with living on top of a hill which is why the cold water pressure is high. Can I adjust the pressure without a PRV to match the hot water pressure?

I will adjust the DHW to what is comfortable as sometimes I have it on in the middle but it is too hot but at certain times of the year the seasonal changes affect the water temperature not sure why.

 

[Chuck]

I will adjust the DHW to what is comfortable as sometimes I have it on in the middle but it is too hot but at certain times of the year the seasonal changes affect the water temperature not sure why.

The water should come out no hotter than the thermostat setting, but it might be cooler in cold weather or if the flow rate is high.

Otherwise, you might have a faulty sensor in the boiler. Get the engineer to check at the next service, or sooner if there is a risk of someone scalding themselves.