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

 

[doitmyself]

In which document did you find the instructions about changing the pump settings? It's not in the Installation and Service manual for the CDi Classic erp.

 

[John.g]

Hi I've attached pics of the hallway trv value which has some writing on it and the water flows in to the rad via it which I'm not sure is correct. I've also attached a pic of the trv valve on the small rad which seems to be making the difference when open (downstairs rads fairly quiet) and closed (downstairs rads sound like high pressure water is going through them). That valve has no writing on it but appears to have writing of some marks the backside of it which I can feel with my fingers, the water is entering the rad via it. I've also attached a pic of the locking valve on the lounge rad that looks like it has seen better days.

I shoudl also add this morning I checked for air in the system again and found some in the highest rad (tall bathroom towel rail) and a bit in my bedroom rad. I was a little supprised as I only checked a couple of weeks ago (maybe 3 or 4!) and sorted it.

I also opened all trv's to 5 this morning to get the air out and after turned the heating up. Most of the rads I could hardly tell were on, no sound. The hall rad I could but it was much quieter than usual. However I noticed the front lounge rad and the hall rad even though they were getting hot at the top they were a fair bit cooler near the bottom and also on the exit pipes there was a big drop off in temperature and the lounge one especially was still basically cold after 10 mins so I gave the lock values on both half a turn and this has improved it somewhat.

I finally went up stairs and turned the trv on the small rad which appeared to be causing the issues down to zero again, went back down stairs and yep all the noise is back. Basically the hallway and lounge rads sound like water is going through at a high rate. The new tall rads in the rear lounge and kitchen also sound the same but less so.

So I am thinking maybe the offending rad had the trv on the wrong end. Maybe the hallway and lounge valves need changing and I'm also wondering if there might be sludge in the hallway and front lounge rads as they are fairly old. That might also be the case with the offending rad upstairs.

By the way is that Vaughan Williams in the pic ?

I have 8 rads with TRV's, (and 2 without) all mounted horizontally on the returns as I reckon it gives far more representative room temperature sensing due to the lower rad radiated temperature if mounted vertically (the more "normal" way) on the flow side, also a uni directional TRV, if mounted horizontally on the return, will still be correct, ie , the flow from underneath the valve seat, I can run my 6M pump at its highest (normally set to 4M PP mode, OFCH) fixed speed setting and still get no noise from the TRVs etc, I will hear a bit of a "pebbly" sound from the pump possibly due to it nearing cavitation at this excessive setting. I have seen uni directional TRVs mounted the wrong way round without any noise issues (can't comment on the control accuracy) so just wonder if your problem has much to do with the TRVs, sounds more like a entrained air problem to me. Can you temporarily change the flow temperature to say 60C to see if the noise dies down, some systems seem to have incurable noise problems if the flow temp is > 70C.
Should also perhaps mention that I have all l/shield valves fully open as I have no detectible balancing problems.

 

[swebb99uk]

In which document did you find the instructions about changing the pump settings? It's not in the Installation and Service manual for the CDi Classic erp.

I found the info the service engineers documentation online

here
[automerge]1578833924[/automerge]

I have 8 rads with TRV's, (and 2 without) all mounted horizontally on the returns as I reckon it gives far more representative room temperature sensing due to the lower rad radiated temperature if mounted vertically (the more "normal" way) on the flow side, also a uni directional TRV, if mounted horizontally on the return, will still be correct, ie , the flow from underneath the valve seat, I can run my 6M pump at its highest (normally set to 4M PP mode, OFCH) fixed speed setting and still get no noise from the TRVs etc, I will hear a bit of a "pebbly" sound from the pump possibly due to it nearing cavitation at this excessive setting. I have seen uni directional TRVs mounted the wrong way round without any noise issues (can't comment on the control accuracy) so just wonder if your problem has much to do with the TRVs, sounds more like a entrained air problem to me. Can you temporarily change the flow temperature to say 60C to see if the noise dies down, some systems seem to have incurable noise problems if the flow temp is > 70C.
Should also perhaps mention that I have all l/shield valves fully open as I have no detectible balancing problems.

Hi thanks for the response. My heating is actually set to 61 normally. I am beginning to think the mixture of all the TRV's of different ages isn't the best of situations, so maybe I would be better getting all the old ones and lockshields replaced.

 

[doitmyself]

I found the info the service engineers documentation online

Thanks. It didn't come up in any searches I did on the WB website

 

[swebb99uk]

Thanks. It didn't come up in any searches I did on the WB website

Yeah no problem, I had to search for it, it doesn't come up on their website for some reason !

 

[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.