I have a DHW secondary pump running through the house. When it comes on my HW tank drops by 18'c. I know that I should expect a drop but this big? We have a 320 l tank. Is there any other reason than just the pipework being so long that could cause this? thanks
DHW Secondary circulation - help!
- Thread starter lissas
- Start date
Sponsored Links
The circuit should be extremely well insulated.
20mm wall Armaflex minimum.
The return should be small bore. 15mm.
Maintaining the temp in the distribitution circuit is an extension to the amount of hot water stored.
So no less important than the cylinder itself when it comes to insulation.
However if you turn the pump on manually lets say once a day or its timed that way then it may cause that temp drop regardless of insulation.
20mm wall Armaflex minimum.
The return should be small bore. 15mm.
Maintaining the temp in the distribitution circuit is an extension to the amount of hot water stored.
So no less important than the cylinder itself when it comes to insulation.
However if you turn the pump on manually lets say once a day or its timed that way then it may cause that temp drop regardless of insulation.
A
ALEC1
not sure what the last sentence means...
I would time it to match likely usage, and put a thermostat on the return...
they are very wasteful...but if you engage with a time clock then you can at least control it...
I would time it to match likely usage, and put a thermostat on the return...
they are very wasteful...but if you engage with a time clock then you can at least control it...
the capacity of the loop is very relevant.
How much water is in the pipe?
Is it within the heated part of the house?
How cold was it when you ran the test?
However well insulated the pipe, after the water has been standing for some hours, it will be cold.
How much water is in the pipe?
Is it within the heated part of the house?
How cold was it when you ran the test?
However well insulated the pipe, after the water has been standing for some hours, it will be cold.
Sponsored Links
Yes, how long roughly is your DHW loop?
Some sort of response from the OP would be nice....... 
Thank you for your responses. The pipes are very well insulated and tend to be 22 with 15 to the taps. All the pipes are within the heated part of the house. It was 10'c when i tested it the other day.
Its a 3 storey house with the HW tank in the basement. It appears that the pipes go to the top of the house first instead of the kitchen etc which is very frustrating. It feeds 4 bathrooms, 3 ground floor basins and the kitchen tap.
The hot water tank tends to be say 52-54'c so even if i put the pump on timed a few times a day if someone wants to shower etc just after the pump has been on the HW temp is then 30-34'c and it takes a long time to recover As this was not an option I currently dont have the pump on while i'm trying to fix this problem and have to wait a long time for hot water
I've been contemplating renting a thermal imaging camera to make sure the loop is going to the correct places.
Its a 3 storey house with the HW tank in the basement. It appears that the pipes go to the top of the house first instead of the kitchen etc which is very frustrating. It feeds 4 bathrooms, 3 ground floor basins and the kitchen tap.
The hot water tank tends to be say 52-54'c so even if i put the pump on timed a few times a day if someone wants to shower etc just after the pump has been on the HW temp is then 30-34'c and it takes a long time to recover As this was not an option I currently dont have the pump on while i'm trying to fix this problem and have to wait a long time for hot water
I've been contemplating renting a thermal imaging camera to make sure the loop is going to the correct places.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
