Opening upstairs rad reduces noise in downstairs rads !

[swebb99uk]

Hi, a bit of advice required.

I've been getting a lot of fast water flowing sounds from three radiators downstairs but not all and upstairs they are quiet, well most of the time. I've bled the system 3 times and also played around with the locks and balancing the system. I can make small improvements but not much. This system is running on a new Worcester Bosch CDI combi boiler.

Last night I noticed that if I opened two radiators upstairs in a room i usually don't heat the noise in the downstairs rads reduced by about 50%. If I closed the rads back off again using the TRV's the sounds came back. I played around opening these two rads in combination and one in particular makes the difference but I really need both open to make the big difference. Interestingly if I don't open the one which makes the big difference I can hear the gushing water sound in the other.

Why would opening a couple of rads upstairs (and only two in particular) cause the nouse in three rads downstairs to decrease ? I don't undersand how they can have that effect. Opening and closing any other rads upstairs has not effect at all. As far as I remember the pipes that came out of the boiler went in to the kitchen and then branched off two going along under floor to the lounge and feeding the downstairs rads and two staying at kitchen ceiling level going under the bathroom floor and feeing upstairs.

I should add I've been in the house 3yrs and the heating has always been fairly noisy and I recently had an extension fitted and a new CDI boiler fitted with a couple of extra rads downstairs. I had hoped this would have improved the noise but if anything it is worse.


Any idea's ?

Thanks

 

[ShaunCorbs]

trv noise i would say prob doesnt happen as the trv is shut eg room upto temp so close one trv at a time a day and see if the noise happens in the next morning again

 

[swebb99uk]

trv noise i would say prob doesnt happen as the trv is shut eg room upto temp so close one trv at a time a day and see if the noise happens in the next morning again

Good idea thanks for that, I'll give it a try.

 

[doitmyself]

How can one cycle it sound like high pressure water shooting through the system and the next be almost silent. The pump is now set on a constant medum speed so its not like it is going through different speeds I wouldn't have thought.

Actually I now wonder if I'm write about the speed being fixed, as I have set the map to constant pressure middle (number two on graph) and H is residual heat and the V volume of water then it looks like if the system starts from cold (morning) then the volumne is a fair bit higher so i guess the pump is a fair bit higher (its sounds like that near the boiler). In which case this would explain the sound of rushing water in the rads.

Constant speed and constant pressure are not the same thing. If a pump is running at constant speed the graph of pressure against flow will be like the traditional pump graph e.g speeds 1, 2 and 3 of a UPS Selectric 15/50

Constant pressure is achieved by varying the speed as the flow varies.

By the way, H is the head, i.e pressure, not heat; and V is the flow, litres per sec.

As for your noise problem, it sounds as if the water is travelling too fast through the pipes. This suggests that the system has not been properly balanced. This is not surprising if it has been done with the pump set to a proportional pressure setting. One of the fixed speeds has to be used.

An automatic bypass has been suggested. If it is installed the pump will have to be on a fixed speed. If a proportional pressure setting is used the ABV will not work correctly; and if a constant pressure setting is used the ABV will be either always open or always closed.

 

[swebb99uk]

Constant speed and constant pressure are not the same thing. If a pump is running at constant speed the graph of pressure against flow will be like the traditional pump graph e.g speeds 1, 2 and 3 of a UPS Selectric 15/50
View attachment 42227

Constant pressure is achieved by varying the speed as the flow varies.

By the way, H is the head, i.e pressure, not heat; and V is the flow, litres per sec.

As for your noise problem, it sounds as if the water is travelling too fast through the pipes. This suggests that the system has not been properly balanced. This is not surprising if it has been done with the pump set to a proportional pressure setting. One of the fixed speeds has to be used.

An automatic bypass has been suggested. If it is installed the pump will have to be on a fixed speed. If a proportional pressure setting is used the ABV will not work correctly; and if a constant pressure setting is used the ABV will be either always open or always closed.

Great thanks for reply, some really useful stuff. Yes I balanced it whilst in proportional high pressure mode so that's highlighted a problem and my large bathroom towel rail has two none trv vales so I believe it's acting as a bypass.

Sounds like I should set in fixed speed mode 4 or 5, balance and then move back to proportional and see what happens!

Thanks

 

[swebb99uk]

Hi all just thought I'd update on this.

I've now had three old rads replaced and most of the trv's and lock sheilds on the other rads. I'v also had one extra rad added and in all my verticle rads I've had diverter values installed (none were from the factory WTF!).

It's now heating the house up quicker and the noise is almost to a level where I can hardly hear anything is on. One interesting thing is the plumber basically said have all the lock valves fully open on these new EU spec'd WB boilers unless there is an issue of heating one or more rads. So thats what I now have. I also have no TRV on the hallway radiator and I will shortly be moving my nest controller in to the hallway and using the TRV's in the longe to control the heating in that room rather than the controller.

Thanks for the advice.