Noisy vibration from Ravenheat CSI Primary

[andy72]

OK, tried boiler pump on setting 3, pretty much same effect as when going from 1 to 2, just reduces the noise a little, but certainly doesn't get rid of it. As expected, it dropped the temp. diff down to about 10 deg C. But boiler still noisy.....

The 22mm lockshield valves are installed just above the boiler as there are no valves on the boiler. Without these I would have to drain the store to do any work on the boiler, hence their installation. I'm sure they are full bore. But these have always been on the boiler from the start, when it didn't make a noise....

I think you're idea about testing with cover off is the next step. Must admit to a little apprehension with this one though !

I think you may have misunerstood one of my previous posts - the boiler doesn't cycle, it's the store that starts and stops the boiler. Only if I set the boiler burner too high ( not thermostat ) does it cause the boiler to cut out. I always have the boiler set to max on the stat., and then let the store keep the boiler running until it is up to temperature, at which point it shuts down the boiler. So from the store requesting heat it is just one long burn until it is satisfied, at which point it shuts down the boiler. No cycling.

This is intentional. General plan is that the mixer keeps the temperature down as low as possible until the store is nearly full, then it starts to increase. Stat on store is set such that it'll cut the boiler out before the boiler gets anywhere near it's own max. setting. Hence no cycling of the boiler. Boiler stat is 85 deg C according to manufacturer.

The boiler manufacturer states a temp. diff. of 20 as ideal, so anything less can't be an issue.

Maybe I should send you an mp3 of the noise.....

Not sure if I'll have much time to play today, family visiting so not a good time to be playing with the heating !

Andy

 

[andy72]

..and I didn't mean lockshield valve. My mistake, they are actually gate valves.

Andy

 

[Agile]

A gate valve with the wheel head is virtually a lockshield valve if you do up the gland not tight!

The important thing is that the gate valve is a full flow type.

I am assuming this boiler is the hybrid type with a modulating coil on the gas valve.

If the PCB power supply smoothing capacitor is failing the PCB can cause a 100 Hz buzz from the mod coil when it modulates back from full power.

I would check that by:-

1. Listening to it !

2. Removing mod coil connection !

3. Looking at the applied voltage with a scope !

4. Adding a temporary smoothing capacitor across the mod coil !

However, some of those apart from No. 1 may be beyond some DIYers.

Tony

 

[Slugbabydotcom]

OK, tried boiler pump on setting 3, pretty much same effect as when going from 1 to 2, just reduces the noise a little, but certainly doesn't get rid of it. As expected, it dropped the temp. diff down to about 10 deg C. But boiler still noisy.....

About 10ºC is a bit vague a more precise figure would help to indicate if the pump is weak

"Reducing the noise a little" denotes a modicum of success as did "increasing the burner pressure" so maybe there is something in that as Tony is thinking

The 22mm lockshield valves are installed just above the boiler as there are no valves on the boiler. Without these I would have to drain the store to do any work on the boiler, hence their installation. I'm sure they are full bore. But these have always been on the boiler from the start, when it didn't make a noise....

I'm fairly happy with that although wont rule out a primary flow restriction in general

I think you're idea about testing with cover off is the next step. Must admit to a little apprehension with this one though !

I'm apprehensive when I do it too. Risk assessment being the order of the day especially if its windy. make sure no one will open a door or otherwise cause a draught and keep your head away to the side if possible. If you can smell gas in there check that the gas valve isn't passing. I often wave my gas leak sniffer in there just to be sure

I think you may have misunerstood one of my previous posts - the boiler doesn't cycle, it's the store that starts and stops the boiler. Only if I set the boiler burner too high ( not thermostat ) does it cause the boiler to cut out. I always have the boiler set to max on the stat., and then let the store keep the boiler running until it is up to temperature, at which point it shuts down the boiler. So from the store requesting heat it is just one long burn until it is satisfied, at which point it shuts down the boiler. No cycling.

This is intentional. General plan is that the mixer keeps the temperature down as low as possible until the store is nearly full, then it starts to increase. Stat on store is set such that it'll cut the boiler out before the boiler gets anywhere near it's own max. setting. Hence no cycling of the boiler. Boiler stat is 85 deg C according to manufacturer.

The boiler manufacturer states a temp. diff. of 20 as ideal, so anything less can't be an issue.

OK the boiler doesnt cycle ....... unless as you say

Setting the blender too high does cause the boiler to cut out, resulting in the boiler cycling unneccessarily.

Perhaps setting the blender higher and increasing cycling could be a move towards the solution

This is how Gledhill see the temp diff situation:-
The primary pipework connecting the boiler and the thermal store should be sized
to achieve a maximum of 11°C rise across the boiler or the maximum temperature
rise specified by the boiler manufacturer, whichever is smaller, but in any instance it
should not be less than 22mm copper tube.
If the boiler is a condensing type the boiler must be set to operate at a normal 82ºC
flow 71ºC return system.

Now I know that you dont have a Gledhill there but their systems are similar enough with regards to this issue IMO to warrant consideration of their recommended practices. I did find their instructions more elaborate. Maybe it is worth your while to contact your manufacturer for technical advice or have a look at the MI's for other similar makes of heatstore.

Maybe I should send you an mp3 of the noise.....

Good idea ! Try putting it on youtube and posting the link.
We are still barking up different trees here as we cannot see or hear the job or do tests.

 

[andy72]

I remember in the early stages of this boiler, when I installed it, that the person I spoke to at Ravenheat stated that I should have the flow to the boiler from the store at the *lowest* temperature possible in order that the condensing function of the boiler worked.

Setting the boiler to 82 deg C will effectively remove any benefits from having a condensing boiler.....although if it gets rid of the noise !

Andy

 

[Agile]

I am assuming this boiler is the hybrid type with a modulating coil on the gas valve.

If the PCB power supply smoothing capacitor is failing the PCB can cause a 100 Hz buzz from the mod coil when it modulates back from full power.

I would check that by:-

1. Listening to it ! With a stethoscope etc.

2. Removing mod coil connection !

3. Looking at the applied voltage with a scope !

4. Adding a temporary smoothing capacitor across the mod coil !

Why dont you at least try No. 1 ?

Tony

 

[Slugbabydotcom]

I remember in the early stages of this boiler, when I installed it, that the person I spoke to at Ravenheat stated that I should have the flow to the boiler from the store at the *lowest* temperature possible in order that the condensing function of the boiler worked.

Setting the boiler to 82 deg C will effectively remove any benefits from having a condensing boiler.....although if it gets rid of the noise !

Andy

When you use a primary boiler in conjunction with a heat store a lot of the normal rules for setting up a boiler in a conventional system are thrown out of the window.

You just found one of the aforementioned defenestrated rules

 

[andy72]

Well, eventually got around to trying out running the boiler with the front panel off, and it does seem to be pointing towards the main heat exchanger as being the main culprit.

When I tried it the temeperature was not up to the point where it is the noisiest, so I need to try again, but the fan seemed fine, and the condensind heat exchanger seemed fine too.

Once I've had chance to test again then I'll have more info. Just wanted to get the boiler back together to run as normal and get the heating running. It's been -5 deg C here for the last few days....

Andy