View Full Version : Themostats on heatpumps on radiators

04-12-2015, 09:00 AM
Can someone helps we have 11 rads and 4 of them make a bad rattling noise we change these and there still making a noise between 1 to 3 setting 3 to 5 works good our temperature setting is set 45 degrees

04-12-2015, 08:27 PM
On the noisey radiators, change the thermotatic valve to the other
side as they can be noisey if fitted on the wrong side.

04-12-2015, 08:56 PM
We done that still no luck

07-12-2015, 08:50 PM
If the pump speed is too high, then as the TRV closes and causes a restriction, this sometimes causes vibration within the TRV. Make sure that the pump speed and the bypass valve are set up correctly.
If the pump is inverter driven, then it should adjust its speed according to the setting of the system resistance.

09-12-2015, 11:28 AM
Hi we tried the speeds still no luck maybe it's the stats again

09-12-2015, 08:25 PM
How is the system plumbed?

Do you have a low loss header or buffer tank, if buffer is it 2 or 4 port, in series or parallel.

How is the water circulated? - Heat pump circulation pump or seperate one?

What make and size of heat pump?
What other circulation circuits are there? Underfloor heating, DHW ?
How may zones are there ?
a) for the 11 rads
b) in total

What make and model of TRV ? (some can only be installed with the flow in one direction)

What's the pipe type (plastic / copper) and size to the rads?

Have you tried swapping one of the noisy TRV's with one that isn't ?

install monkey
10-12-2015, 07:40 PM
1 radiator needs to be a bypass- fully opened on lockshield and trv- otherwise a bypass valve needs fitting accross flow and return

11-12-2015, 10:58 AM
Those noisy ones are which get most of the system diferential pressure!
Thermostatic radiator valves are designed to work with certain pressure differential across them ( usually 10-40 kPa).
If pressure differential is rising above that at valve closing, it can become noisy!

You have issue with balancing at radiators! You need proper balancing. With thermostatic radiator valves, static balancing with return valves is not option. You need dynamic balancing. That can be done with differential pressure regulators at each circuit branch or flow regulators! How many of them, depend on system layout.


If whole system is one branch, than you should use pump with differential pressure regulation (internal, or in combination with diferential pressure valve) .

Also, you need radiator valves with capacity regulation adjusted for every radiator according to radiator power output (if flow regulator is not used):

Or you can use these valves:

And, aside from that, radiator valves are dimensioned for Δt of 10K or more.
If you are using normal Δt of 5K for heat pump for fan-coils, than your radiators don’t have sufficient power for heating!
Your heat pump should be of type which could work with 10K Δt and designed to work with radiators as heating elements.

12-12-2015, 08:42 PM
Hi these valves are caleffi we done what you guys said and still have a noise problem never had a problem at the start of the job a year ago

14-12-2015, 07:42 AM
Than measure differential pressure at these rattling ones and you will know if it is because of valve or because of high differential pressure. Since you changed valves and problem is still there, I bet on pressure! It is not properly adjusted or properly maintained!

14-12-2015, 08:04 AM
This system only a year old was put on for 2 months last year run great only been running for 3 weeks and now noise problems hard to find good labour in this country Nike 123

14-12-2015, 08:43 AM
Can you post here drawing of system with each regulation component of system in drawing with its model number?
Also, mark valves on drawing which are noisy!