New radiators problem

debbiebosh

We had most of our radiators replaced last winter and have had to have our plumber back several times due to how noisy some of them they are. Mix of gushing, tapping and hissing sounds. Typically it's the bedrooms and living room which are thex noisiest so very annoying. Our plumber has tried:

Silencer liquid put through for boiler noise reduction 

Autovents fitted to 2 bedroom rads 

Filter on boiler 

Our bedroom rad gets very loud after we use the taps in our ensuite. 

Noise can stop when thermostat turned up or down but I shouldn't have to keep adjusting. 

Boiler is Logic combi c30.

Making us very stressed. My daughter can't sleep if her rad is on and I can't set heating for before we get up as it's just too noisy. Wishing we'd just left old rads on. Only got replaced as they were very old and thought be ones would be more efficient but were silent when on. 

Advice please! 

FreeBear

Normally, I would say turn the pump speed down, but with a combi, it is fixed by a menu option during boiler installation.

I'm wondering if your plumber has balanced the radiators properly and tried setting them for too greater temperature drop - One normally aims for a 10-12°C drop between flow & return, but at the higher end, it can restrict flow too much. One radiator I fitted here, I had to go for an 8°C drop so that it would heat up at an acceptable rate and also reduce the noise (a kinda hissing sound).

Gurgling is usually associated with trapped air, so it might be worth going round and bleed every radiator again.

Tapping noises could be a copper pipe expanding/contracting - I would get a ticking noise as one length of pipe got hot due to some tight pipe clips with a strong grip.

ThisIsWeird

As FreeBear says.

The 'tapping' noise - is that a steady repeated 'tick', or more a 'rattle'?

Could you post a photo of the most offending rad, along with close-ups of its two valves, please? We can then suggest some things to try.

(Do you know how to bleed rads? If so, could you try this on any gurgling rad? Boiler off during this process.)

Interesting about how the noise changes when you turn on a tap. That will be the hot tap, presumably? Inside the boiler is a motorised valve that diverts the boiler's hot water to either the radiators or to heat your DHW. When you turn on a hot tap, that takes priority, so the CH actually stops receiving circulated water as long as the tap is on. When you shut off the tap, the CH starts up again = noise.

debbiebosh

I'm new to this and have been trying to reply but it keeps disappearing! 

The noise is more of an irregular rattle and not consistent. We have bled all the rads and 2 of the bedroom offenders now have autovents fitted which I'm told is to auto bleed. Fitting these has made no difference, were fitted in spring when we'd just stopped using rads so only noticed this week that when they were fitted the plumber took the TRV off so we've asked him to come back and put it back on.
Yes the extra gushing only happens with hot tap  and not cold and none of the noise occured with the old rads.
We will ask plumber about the temperature drop range.

ThisIsWeird

Could you pull off these white plastic caps, please, and photograph what's underneath?

How do you control the heating output of these bedroom rads? Are they always 'on' to some degree? Does that mean they are on all evening when the main heating is on? Is it on even during the day?!

Any idea why the plumber removed the TRV heads?

You had these fitted in order to update the aesthetics? Was there not a larger ize that would have negated having to use such a clumsy-looking pipe adaptation? A larger rad could also be run 'cooler' to provide the same output, and that could have some (admittedly very minor, since only a couple of rads involved) efficiency benefits too.

Size of current rad, please?

And, when you turn the heating on, which of these ends become hot first?

debbiebosh

We have a heating thermostat for the whole house so they are on whenever we have heating on, every evening and varying during day. All other rads have TRV and no idea why he took TRV off this one. 
Couldn't get a rad to fit exactly, this was the best option. The ugly pipes are hidden by curtains so I'm not worried. It's 119 x 64cm.  The right hand side warms up first.

ThisIsWeird

Thanks for that.
Clearly a waste of energy running a rad when it's not actually required, but hey.
Ok, the LH valve is a normal 'lockshield'. That one is set to provide the correct glow to that rad, relative to the others - IE it 'balances' the system. That one is fine.
The other end is a whathehell? It looks broken. But hopefully a plumber on here will confirm.

greyteam1959

There is certainly something amiss with the valve in your first picture.
It looks to me like a broken TRV but I might be wrong.
I would be getting the plumber back to sort this out or getting out a real plumber who knows what he / she is doing.
Do those auto bleed valve actually work ?
Are all the radiators with them hot at the top ?

debbiebosh

Thanks all, I'll speak to the plumber when he's back next week

Vortigern

The valve on the right looks like the bottom part of a TRV. There should be a pin in the middle that the proper head would push down to reduce the flow. Has the pin broken off?  

The cap on that valve could be a decorator's cap, used temporarily to protect the valve while you're painting. These would normally screw down and close the valve.