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Hi,

 

I have recently purchased a boat and after moving on have discovered that there is no hot water coming out of the hot tap. The water does get hot just doesnt come out of the hot taps. (Cold tap has water ok) The boat is fitted with a brand new surecal 55ltr vertical calorifier with a drain valve at the bottom and the PRV and Mixer tap at the top. (Fitted by the previous owner but never comissioned)  The cold water feed from the pump (at the front of the boat) feeds the taps and shower before reaching the calorifier in the engine bay. It then feeds into the bottom of the calorifier and also has a T-piece off the bottom of the feed that feeds into the mixer valve at the top.   I did notice that if I turn the red cap on the TRV to the open position water comes rushing out of the hot tap but stops as soon as I release/close it.  Does anyone have any ideas on what the issue might be as I dont want to keep the PRV permanently open just to get hot water.  My install appears to mirror the connection instructions from surecal except on my calorifier the PRV is also on the top brass part with the mixer valve. (The bottom appears to just be  a water feed inlet and a drain valve)

 

Many thanks in advance.

Sarah

 

My Calorifer:

 

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Surecal Instructions:

 

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53 minutes ago, Sarah-H said:

   I did notice that if I turn the red cap on the TRV to the open position water comes rushing out of the hot tap but stops as soon as I release/close it.  Does anyone have any ideas on what the issue might be as I dont want to keep the PRV permanently open just to get hot water. 

 

Typo or are you getting the Thermostatic Mixing Valve and Pressure Relief Valve mixed up?

Edited by David Mack
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And just to add that with the hot taps turned off, the PRV has no-where to expel over-pressure and so you have a high possibility of over-pressurising the calorifier and having it split. I would get it fixed ASAP!

1 minute ago, David Mack said:

 

Typo or are you getting the Thermostatic Mixing Valve and Pressure Relief Valve mixed up?

Good point. Could the OP post a photo of the top area?

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2 minutes ago, David Mack said:

 

Typo or are you getting the Thermostatic Mixing Valve and Pressure Relief Valve mixed up?

Oops sorry that was a typo.  If i twist the red PRV knob as per the 1st picture above water comes out of the hot taps but stops as soon as I release it.

Just now, Loddon said:

Does any water come out of the hot tap?

 

Hi,  No, I get no water at all out of hot tap unless I 'open/twist and hold' the PRV red knob on the calorifier.

 

Thanks

Sarah

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4 minutes ago, Sarah-H said:

Oops sorry that was a typo.  If i twist the red PRV knob as per the 1st picture above water comes out of the hot taps but stops as soon as I release it.

Hi,  No, I get no water at all out of hot tap unless I 'open/twist and hold' the PRV red knob on the calorifier.

 

Thanks

Sarah

Well in that case, as I initially thought, the PRV outlet must be connected into the hot water system. It must instead be vented overboard or into the bilge. Sounds like the installer got confused between the PRV and the thermostatic mixer. As I said, the way things are you risk wrecking the Calorifier in short order.

Edited by nicknorman
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1 minute ago, nicknorman said:

Well in that case, as I initially thought, the PRV outlet must be connected into the hot water system. It must instead be vented overboard or into the bilge. Sounds like the installer got confused between the PRV and the thermostatic mixer. As I said, the way things are you risk wrecking the Calorifier in short order.

After having looked at the instructions supplied with the calorifier again I can see this might be the case as the image supplied does not quite match up with the calorifier supplied. If that was the case however, wouldn't water come out of the intended how water outlet?

 

Thanks

Sarah

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4 minutes ago, Sarah-H said:

Oops sorry that was a typo.  If i twist the red PRV knob as per the 1st picture above water comes out of the hot taps but stops as soon as I release it.

That's weird! Are you sure that the pipe feeding the hot taps is connected to the TMV at the top of the calorifier?

If your calorifier is like the top image, the hot water pipe should be connected to the outlet next to the black knob, and the outlet next to the red knob should lead overboard or to the bilge.

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4 minutes ago, David Mack said:

That's weird! Are you sure that the pipe feeding the hot taps is connected to the TMV at the top of the calorifier?

after reading nicknormans post above, I'm now not sure.  It certainly seemed to be according to the image instructions supplied with the calorifer and included in my boat file but as this image clearly relates to a different calorifier the hot water pipe may have been fitted to the PRV outlet by the previous owner and not the tap by the mixer valve.  I'm not at the boat at present but will get a pic as soon as I am back home.

 

Thank you.

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6 minutes ago, Sarah-H said:

After having looked at the instructions supplied with the calorifier again I can see this might be the case as the image supplied does not quite match up with the calorifier supplied. If that was the case however, wouldn't water come out of the intended how water outlet?

 

Thanks

Sarah

You’d think so, but maybe it is capped off. Something is very wrong with the way it is connected, anyway!

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2 minutes ago, nicknorman said:

You’d think so, but maybe it is capped off. Something is very wrong with the way it is connected, anyway!

Yes, Im getting worried now! last thing I need is an expensive calorifier replacement or a scalding hot explosion!  Looking at the 1st image above (Just the actual calorifier) where would you say the hot water outler should be connected?  The left spigot(?) or the one directly behind the mixer valve (Sounding more an more likely!)

 

Thank you so much for your help so far!!

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On that image  the left spigot is the PRV outlet so goes overboard   or into the (engine room) bilge.

 

The spigot on the right is probably the cold water inlet for the thermostatic mixing valve so that leaves the one at the back to be the hot water out let but I would be looking for arrows on the mixing valve body to confirm.

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2 minutes ago, Tony Brooks said:

On that image  the left spigot is the PRV outlet so goes overboard   or into the (engine room) bilge.

 

The spigot on the right is probably the cold water inlet for the thermostatic mixing valve so that leaves the one at the back to be the hot water out let but I would be looking for arrows on the mixing valve body to confirm.

Agreed. One can see how the installer has been suckered into connecting it wrongly by looking at the diagram, which shows the HW connection top left, whereas according to the photo that is the PRV outlet.

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7 minutes ago, nicknorman said:

Agreed. One can see how the installer has been suckered into connecting it wrongly by looking at the diagram, which shows the HW connection top left, whereas according to the photo that is the PRV outlet.

I had to look at it a few times to work out which angle they were looking at... it doesn't help that the immersion heater is in the wrong position in the diagram wrt the top connections (as compared to the photo). It should be off to the right, not on the centreline.

 

Edit: and of course all the side connections are in the wrong place. They've basically rotated the top pipe assembly through 90 degrees - something that it's unlikely you could do in real life without the PRV fouling on the immersion.

Edited by phantom_iv
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The thermostatic mixer may have a red knob as well to adjust the temperature.

As we don’t have a photo, I will say that the valve with 3 pipe connections to it is the thermostatic mixer.  The prv will probably be mounted directly on the tank, but could be close by on one of the pipes.  The outlet from the prv may or may not have a pipe connected depending on where it dumps it’s water, but is must never go back into the water system.

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46 minutes ago, Sarah-H said:

After having looked at the instructions supplied with the calorifier again I can see this might be the case as the image supplied does not quite match up with the calorifier supplied. If that was the case however, wouldn't water come out of the intended how water outlet?

 

Assuming the diagram's been misread and the hot water pipe is connected to the PRV outlet then I'd suspect the cold intake for the mixer valve is actually connected to the mixer valve outlet (as this would be consistent with the same misreading of the orientation). Given the cold feed has a non-return valve built in, this would prevent any water coming out even if left uncapped.

Edited by phantom_iv
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17 minutes ago, Tony Brooks said:

 

The spigot on the right is probably the cold water inlet for the thermostatic mixing valve so that leaves the one at the back to be the hot water out let but I would be looking for arrows on the mixing valve body to confirm.

 

If you Google pictures of thermostatic mixing valves they all seem to have the hot and cold water inlets on either side, with the regulated temperature water out at the opposite end to the knob. So I agree with Tony. But check for arrows on the TMV body, or markings denoting the hot and cold inlets.

  • Greenie 1
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I am wondering if the calorifier came fully assembled, or whether the PRV was a separately wrapped part, and not fitted. There is no doubt that it is fitted in the hot water supply line, whereas the Surecal instructions show it at the bottom of the tank.

 

If it was mine, and subject to actually being able to see it, I might be tempted to remove the PRV and fit it where it looks like it should go, and reconnecting the hot supply without it.

 

If not DIY oriented I would probably get an installer, (not the one who fitted it), recommended perhaps from here, and ask them to sort it out.

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The actual position of the PRV will not matter, Pascal's law says pressure is equal throughout a system so as long as there is no one way valve between the PRV and calorifier body it will be fine. My PRV is right at the front of the boat by the  pump but I don't have a one way valve on the calorifier inlet.

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34 minutes ago, Sarah-H said:

Hi everyone,

 

Sorry for the delayed response but I left work early as I panicked over possibly having left the immersion on! 

 

Thank you to everyone for their advice and suggestions and I'm pleased to say the problem is now resolved.

 

As advised I managed to get into the engine bay, undid the mounting bolts and tipped the calorifier towards me enough to see on the mixer a few embossed letters indicating which spigot was H-hot, C-cold and M-mixer and it became apparent that the previous owner had indeed connected the hot water pipes to the PRV connection and the cold pipes to the mixer feed! (Having looked at the above image/instructions I can see why he did this and can only assume the calorifier was in situ when he plumbed it and didnt see the lettering on the mixer. 

 

Quick trip to local plumbers merchant for some speedfit parts and reconnected everything to where it should be and I now have hot water to the taps and PRV plumbed to the bilge. 

 

For a non techie I'm so pleased I could fix it without the expense and hassle of an engineer! (Especially as the last 3 that I booked to look at it failed to turn up!)

 

Anyway, thank you all so much for your help and advice  it has been very much appreciated!

 

Sarah. Xxx

 

Ps: the installation instructions i found earlier on the surecal website for this calorifier are not the instructions for this calorifier so anyone fitting these please beware! 

You now need to fit an expansion vessel so that the PRV doesn't keep opening, I doubt from what you said the last owner fitted one.

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