Danfoss trvs hard to balance rads

[Sime]

Hi, I put a new central heating system in my property 3 years ago and used danfoss trvs. I have never managed to successfully balance the radiators using these trvs and wondering now if I've fitted them properly. It's a fine line from hot to warm eg each trv has 5 heat settings but heat setting 2 is just as hot as a fully open valve on heat setting 5, when I turn it down to 1 the radiator is hardly warm. So basically to regulate the heat I have to fine tune the valve between heat setting 1&2. Is this right??

 

[Scott_D]

You dont balance through the trv, you balance through the other valve (lockshield)
The trv just opens or shuts when the air around it reaches the temp zone you set the dial to

 

[Sime]

Ah that's where I'm going wrong. I just don't understand trvs. Need to read more! Thanks a lot

 

[Scott_D]

In a nutshell they close to stop water flowing through the radiator when the room they are in reaches the temperature you want. The room then cools down and the TRV opens again and the radiator get warm

 

[Sime]

Thanks a lot, makes sense now. I'll try again tomorrow.

 

[Best]

Ignore that sometimes the radiator will be hot at each setting. It depends on the room temperature and the Trv head will close off and on as temperature rises or drops slightly.
Think of it as a washer closing off as the head expands.
The balancing of system is done with the lockshield valve on other side of the rads and you should be able to improve the heat performance of your system if you have that done.

 

[CHRISX]

Hello Sime,

When You balance a Heating system the TRV`s should be taken off and the Radiators balanced using the Lockshield Radiator valves - also turn the Room Thermostat to maximum.

Otherwise you would be balancing the system [which usually takes quite a while] and some of the TRV`s could start closing down which would then boost the Flow to other Radiators and cause you to have the wrong impression of what your adjustments of the Lockshield Radiator valves have achieved.

The only way to get the Flow through all of the Radiators even roughly correct requires the use of either a Digital Thermometer or `clip on` Pipe Thermometers which you can move around checking the Flow and Return temperatures of the pipes.

People who state that they `can tell roughly by touch` / don`t need to use Thermometers are obviously on a wind up !

Good Luck with balancing your Heating system.

Regards,

Chris

 

[Sime]

Hi Chris, appreciate your reply. I can see where your comments make a lot of sense.
I tried to balance the radiators last night and got to admit they are a lot better, I have more flow in the bigger radiators on the long runs furthest away from the combi and the radiators closer to the boiler (which heat faster) are more controlled with the lockshield only quarter open. Only problem I found is that theres no guide to what temperature the trvs settings relate to? So I have no idea what the room temperature would be if I turned the trv to (|||) I suppose like you say it will take time and a few more adjustments on the trvs to get the air temp right before the radiator starts to shut off.
Many thanks for everyone's comments, my heating system is probably running the best it can after the adjustments I made.
I now have a better understanding how to balance my system

 

[doitmyself]

A TRV is more like a car accelerator than a switch. It adjusts the flow through the radiator so the heat produced matches the heat lost through the walls etc.

TRV's do not show temperatures for two reasons:
1. The required setting for a given room temperature depends on the conditions;
2. It eliminates the need to produce different heads for Celsius and Fahrenheit.

A setting of 3 or 4 (depending on manufacturer) is equivalent to a temperature of about 20C. When balanced correctly a valve will be fully open when the temperature is 1C below the setting and fully closed when 1C above. This gives a 2C "proportional band" for fine control of the room temperature.

 

[AWheating]

First understand the trv does not control the radiator temperature but the room temperature. Most trvs start around 16-18 degrees at setting one and 28-30 at max setting. Each number or marker being 2-3 degrees of increase. As a rough guide.