Pressure alarm sounding

[rusty69]

53 minutes ago, Jennifer McM said:

Dr Bob you are a STAR! Does the 'infrequent red thermometer come with instructions though ?

 

{In hushed tones} think John should be encouraged to buy one of these for his 'arsenal' tool kit though.

 

Get him to show you his duck too. If it's still alive! 

[TheBiscuits]

1 minute ago, rusty69 said:

Get him to show you his duck too. If it's still alive! 

I had to read that twice.  Rule 34 I think.

 

[rusty69]

1 minute ago, TheBiscuits said:

I had to read that twice.  Rule 34 I think.

 

Good moaning! 

[alan_fincher]

2 hours ago, rusty69 said:

Get him to show you his duck too.

That's one where you need to be careful typing, (or at least have autocorrect disabled!).

[rusty69]

3 minutes ago, alan_fincher said:

That's one where you need to be careful typing, (or at least have autocorrect disabled!).

quack quack oops

[Dr Bob]

4 hours ago, Jennifer McM said:

Dr Bob you are a STAR! Does the 'infrequent red thermometer come with instructions though ?

 

{In hushed tones} think John should be encouraged to buy one of these for his 'arsenal' tool kit though.

 

Being a red, I'm not very keen on Arsenal.

 

ETA.. neither is the duck. Jennifer, you may be needed to confirm said duck still exists.

Edited August 6, 2018 by Dr Bob

[rusty69]

5 minutes ago, Dr Bob said:

Being a red, I'm not very keen on Arsenal.

 

ETA.. neither is the duck. Jennifer, you may be needed to confirm said duck still exists.

Of course the duck aint a "red", he's a "yellow". If he's still alive that is! 

[Dr Bob]

4 minutes ago, rusty69 said:

Of course the duck aint a "red", he's a "yellow". If he's still alive that is! 

His bill/beak/stickyoutthingatthefront is red! A true supporter.

[rusty69]

4 minutes ago, Dr Bob said:

His bill/beak/stickyoutthingatthefront is red! A true supporter.

I thought it was more an orangey colour. Duck a l'orangey. 

[Boater Sam]

On 05/08/2018 at 10:04, Boater Sam said:

Could the alarm not be the normal control panel sounder but the pressure release valve on the calorifier blowing off?

I got there in post 7, any credit ?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

/

[rusty69]

4 minutes ago, Boater Sam said:

I got there in post 7, any credit ?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

/

[Momac]

On 05/08/2018 at 16:22, Tony Brooks said:

Even with a 65 degree engine thermostat the hot water gets close to being unsafe and very hot.

My engine thermostats are intended to start to open at 81 degrees 

The domestic water does gets very hot   but I have not known the prv to vent.

More modern boats than mine may have a mixer valve to blend some cold water with the hot just after the calorifier.

 

If a PRV has been  venting is it not best to replace the valve?

The valve on my boat looks like the following , which costs just over £4

https://www.screwfix.com/p/pressure-relief-valve-x/2459v

 

 

[Tony Brooks]

2 minutes ago, MartynG said:

My engine thermostats are intended to start to open at 81 degrees 

The domestic water does gets very hot   but I have not known the prv to vent.

More modern boats than mine may have a mixer valve to blend some cold water with the hot just after the calorifier.

 

If a PRV has been  venting is it not best to replace the valve?

The valve on my boat looks like the following , which costs just over £4

https://www.screwfix.com/p/pressure-relief-valve-x/2459v

 

 

No, its best to find out why its venting and then act appropriately.

 

If the PRV is venting because the domestic pump pressure is too high then fitting a new one will not solev the issue. Fitting one rated at a higher pressure could well result in a split calorifier.

 

I have not seen a definitive diagnosis to this thread yet and as Mike, I think, pointed out referring to the sound the OP was on about as a warning sounder/buzzer is probably very misleading. The only reason PRVs came up is because the OP indicated they thought the sound was coming from that general area.  am far from convinced that is the correct diagnosis so I wait to see what develops. As I said, I can't see a PRV would sound continuously like a warning buzzer because to do that either the domestic water pump pressure would have to be above the PRV pressure or soothing else, like boiling domestic water, would have to be constantly providing excess pressure. As the domestic water system operates at a higher pressure than the cooling system I think its the cooling system that should be boiling, not the domestic water.

 

Anyway I don't like the PRV you linked to, it seems to be adjustable and it will present too much opportunity to set it a bit higher to cover up other problems and the the calorifier is in danger. I think a fixed pressure one at the correct pressure rating would be better.

[TheBiscuits]

53 minutes ago, MartynG said:

More modern boats than mine may have a mixer valve to blend some cold water with the hot just after the calorifier.

They are only a few quid from a plumbers' merchant, and well worth fitting.  Because they mix the (too) hot water with cold, you effectively get more (correct temperature) hot water, and less risk of scalding.

[Boater Sam]

On 05/08/2018 at 10:04, Boater Sam said:

Could the alarm not be the normal control panel sounder but the pressure release valve on the calorifier blowing off?

If the accumulator is either not fitted or not pressurised, there is nowhere for the expansion to go when it heats except through the PRV.

[Tony Brooks]

4 minutes ago, Boater Sam said:

If the accumulator is either not fitted or not pressurised, there is nowhere for the expansion to go when it heats except through the PRV.

But that would be a short burp, not a continuous sound. In fact I suspect the rate of expansion would be such that it would only dribble and I can't see that making a significant noise but who knows.

[Boater Sam]

On 05/08/2018 at 10:04, Boater Sam said:

Could the alarm not be the normal control panel sounder but the pressure release valve on the calorifier blowing off?

 

9 minutes ago, Tony Brooks said:

But that would be a short burp, not a continuous sound. In fact I suspect the rate of expansion would be such that it would only dribble and I can't see that making a significant noise but who knows.

But the op has already said the the noise originates in the calorifier area!!!

[Tony Brooks]

3 minutes ago, Boater Sam said:

 

But the op has already said the the noise originates in the calorifier area!!!

I know that but she does not seem to have investigated further like looking at the PRV outlet, wherever it is, when the sound is present. It might be some odd vibration in pipework,without investigation we simply do not know so are speculating.

[Cyan]

On 05/08/2018 at 17:07, Tony Brooks said:

 

Unless you ave a thermostatic mixing valve on the calorifier hot outlet I doubt the is any thermo control of domestic water supply. I also doubt you have any temperature monitoring on it either. However with a  second-hand boat nothing can be taken for granted.

 

I would be looking in the area where you think the noise was coming from for something like an inverter that may have  been complaining about something.

 

If the pressure switch on the domestic water pump stuck closed then the PRV might make a noise as it constantly vented water.

 

I am very interested as to what is going on.

 

 

 

 

Tony, I have opened up the panel covering the H.W. storage tank, yes there is a PRV on the top of the cylinder which felt 'free' to rotate. No signs of water leakage but am sure this is the source of the 'alarm' noise. 

Swim tank: the area of the tank is 7000cm2 which is equiv to 7.54ft2 with a thickness of 4cms. Using your rule of thumb, 4hp per 1ft2 gives me a cooling tank suitable for 30hp. 

Ideal tank size would be 8.75ft2 for the Izuzu 35 engine in our 57ft N.B. It is reasonable to assume that under canal conditions there is little chance of overheating but on a river with wind, water flow rate to contend with, there is a chance of overheating occurring. Our solution to increase the cooling capacity by running the C.H. circulation pump, utilising the radiators for additional cooling, would appear to fix the rare problem of system overheating when running the engine hard in summer conditions.. Temperature checking will have to wait until I can pick up a suitable I.R. Thermometer!

Thx for your interest and insight

John

[Tony Brooks]

Your PRV as a hose fixed to its outlet so really you need to find the other end. This may be into the bilge beside the engine tray. If it is the PRV making the noise then you should see water drips coming out. But with that noise I would expect a fair flow.

 

The red knob will rotate but you should feel t stiffen and loosen as it jumps the valve itself up and down. This is normal.

 

I agree the tank should be large enough for most cruising, even on rivers for most of the time.

 

The perforated board on the right of the photo interests me, especially with what looks like a yellow mains flex coming through it.  What is behind it? If its an inverter then that may make noises at times.

 

 

Edited August 12, 2018 by Tony Brooks