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I have a large vertical calorifier. The cold inlet, at the bottom (as it should be) has a Hep2O service valve. This has started to dribble, especially when turned off, which sort of defeats the object of a service valve. Actually this has happened elsewhere on the boat and looks to be the only problem with Hep2O, infrequently operated service valves start to dribble after about ten years.

So, I need to replace it with a new one. Sensible approach would be to contrive a pump system to drain the calorifier (I do have a spare fresh water pump and various bits of pipe). Really clever approach would be to find a suitable quiet aquaduct/overbridge or lock and syphon the contents over the side but I don't think there is anything convenient on the Weaver. Draining the calorifier will be a bit tedious so I was sort of thinking, if I de-pressurise the cold inlet, close the service valve on the hot outlet, get everything ready, plus lots of "boat towels" on the floor, and work really really quickly can I do this "live". First fitting is an elbow (previous generation grey Hep2O) so can unscrew cap, leave cap and grab ring in place and have a spare elbow, connected to new service valve, ready to go straight on. I reckon 2 seconds max.  Question is, if it goes wrong, is it going to be a trickle from the calorifier or a raging torrent????? 

 

................Dave

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On mine I have a T on the cold inlet via a valve and then a T between the bath drain and the pump. Opening the valve drains the water into the bath and a plug in the bath and pump on will suck it out, or gravity will just dump it in the bath. If you have a shower there is a risk of overtopping the shower tray.

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26 minutes ago, dmr said:

Question is, if it goes wrong, is it going to be a trickle from the calorifier or a raging torrent????? 

 

A question to provoke thought...

 

If one arranged for no air to get into the calorifier, would the water still come out?

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If there isn't a non return valve on the calorifier inlet you could turn the water pump off, turn off the valve at the tank outlet, connect a drill-operated pump to a cold water tap outlet, open a hot water tap and then pump the entire calorifier contents out from the inlet.

And if there is a NRV on the calorifier inlet, then no water will come out when you disconnect the inlet pipe anyway.

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19 minutes ago, Mike the Boilerman said:

 

A question to provoke thought...

 

If one arranged for no air to get into the calorifier, would the water still come out?

In my experience no. You need to either open a hot water out pipe at the top, or turn the pressure relief valve so it is open to get anytbing more than a dribble from the cold water in. With a pipe cutter for plastic pipe, a bowl and a new speedfit service valve it is possible to change the service valve with little loss of water if the PRV is closed and hot water out is connected. You have to be quick! You can then rearrange the input plumbing once the (off) speedfit valve is on the pipe in to the cauliflower. Have cone this successfully. Speedfit is much quicker to push on than either old, or new style Hep2o. This all assumes there is a length of plastic pipe between the old service valve and the cal.

 

Jen

Edited by Jen-in-Wellies

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1 minute ago, Jen-in-Wellies said:

In my experience no. You need to either open a hot water out pipe at the top, or turn the pressure relief valve so it is open to get anytbing more than a dribble from the cold water in.

 

This is what I was encouraging DMR to conclude, and I'm sure he would have!

 

2 minutes ago, Jen-in-Wellies said:

You have to be quick!

 

No you don't. You have all the time in the world.

 

Cut the pipe (or just pull off the speedfit service valve), casually put your thumb over the end and about half a thimble of water will have been spilled. Then remove your thumb and push-fit on the new isolator you prepared earlier, and Bob etc etc. 

 

Oh and all this presumes there is no non-return valve on the water inlet to the cauliflower, but I bet there is!

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3 minutes ago, Mike the Boilerman said:

 

This is what I was encouraging DMR to conclude, and I'm sure he would have!

 

 

No you don't. You have all the time in the world.

 

Cut the pipe (or just pull off the speedfit service valve), casually put your thumb over the end and about half a thimble of water will have been spilled. Then remove your thumb and push-fit on the new isolator you prepared earlier, and Bob etc etc. 

 

Oh and all this presumes there is no non-return valve on the water inlet to the cauliflower, but I bet there is!

OK, I have an open bottle of cider in front of me (what a surprise!) if I turn it upside down there is no way for the air to get in, but will the cider spill out??? ?

 

There is no none return valve on the cold feed, just a long pipe run, so have never needed one. I am happy about opening the cold water feed, its just a gulp of water that comes out (a very very big thimble), but dumping the entire calorifier contents into the bilge would be a very bad thing. 

 

I intend to install a proper drain cock at the same time to make things easier in future. Will be boating up to Screwfix tomorrow to get some bits.

 

Did have a nasty (and very wet) experience in a house a few years ago attempting a "live" plumbing repair that went very wrong. A tank in the attic and 28mm plumbing can deliver a LOT of water ?

 

..................Dave

 

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23 minutes ago, Mike the Boilerman said:

 

This is what I was encouraging DMR to conclude, and I'm sure he would have!

 

 

No you don't. You have all the time in the world.

 

Cut the pipe (or just pull off the speedfit service valve), casually put your thumb over the end and about half a thimble of water will have been spilled. Then remove your thumb and push-fit on the new isolator you prepared earlier, and Bob etc etc. 

 

Oh and all this presumes there is no non-return valve on the water inlet to the cauliflower, but I bet there is!

then curse because you've forgotten to put the plastic insert (back) in before you put it together.

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12 minutes ago, dmr said:

OK, I have an open bottle of cider in front of me (what a surprise!) if I turn it upside down there is no way for the air to get in, but will the cider spill out???

 

I think you've had too much cider. The cider will come out because air CAN easily get in, Shirley.

 

The calorifier is different because air can only get in by flowing UP the same tiny pipe the water is flowing DOWN. So the opposing flows will obstruct each other massively. 

And the NRV is usually incorporated inside the cold fill connection at the factory. I doubt you'd be aware of its presence unless you looked for it specifically when installing the calorifryer.

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Best pick a warm day and wear your swimming trunks just in case.

 

I tried "live" plumbing once when I couldn't be bothered to drain the home central heating system. At least the calorifier water won't be black!

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24 minutes ago, Mike the Boilerman said:

 

I think you've had too much cider. The cider will come out because air CAN easily get in, Shirley.

 

The calorifier is different because air can only get in by flowing UP the same tiny pipe the water is flowing DOWN. So the opposing flows will obstruct each other massively. 

And the NRV is usually incorporated inside the cold fill connection at the factory. I doubt you'd be aware of its presence unless you looked for it specifically when installing the calorifryer.

Its 2001 boat technology, I had assumed that non return valves where a more recent concept?

 

Anyway, I am been a bit thick here, there is a very easy way to assess the flow before doing anything drastic, just open the cold water feed somewhere with the service valve closed, then open the service valve and see how much water comes out!!!!

 

................Dave

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I don't know when NRVs first made their appearance in cauliflowers. Probably about the same time as consumers started moaning about slightly warm water coming out of the cold taps. Previously peeps were delighted to be getting water at all!

 

But yes, turn off the pump and open all taps until water stops flowing, then turn them all off again. Now you're broadly safe from the torrent you created last time around :)

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1 hour ago, Mike the Boilerman said:

 

 

Cut the pipe (or just pull off the speedfit service valve), casually put your thumb over the end and about half a thimble of water will have been spilled. Then remove your thumb and push-fit on the new isolator you prepared earlier, and Bob etc etc. 

No, Bob doesn't have a clue. He's a chemist, not a engineer!

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1 hour ago, dmr said:

OK, I have an open bottle of cider in front of me (what a surprise!) if I turn it upside down there is no way for the air to get in, but will the cider spill out??? ?

 

There is no none return valve on the cold feed, just a long pipe run, so have never needed one. I am happy about opening the cold water feed, its just a gulp of water that comes out (a very very big thimble), but dumping the entire calorifier contents into the bilge would be a very bad thing. 

 

I intend to install a proper drain cock at the same time to make things easier in future. Will be boating up to Screwfix tomorrow to get some bits.

 

Did have a nasty (and very wet) experience in a house a few years ago attempting a "live" plumbing repair that went very wrong. A tank in the attic and 28mm plumbing can deliver a LOT of water ?

 

..................Dave

 

Can you not break in between the duff valve and the pump, install a drain off then open the valve and drain  it. then change the valve?

 

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6 minutes ago, ditchcrawler said:

Can you not break in between the duff valve and the pump, install a drain off then open the valve and drain  it. then change the valve?

 

 

Why would you need to?!

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4 minutes ago, ditchcrawler said:

Can you not break in between the duff valve and the pump, install a drain off then open the valve and drain  it. then change the valve?

 

Yes I could, but it is quite a big calorifier so that would be a lot of buckets of water to throw out of the window. I reckon it could take well over an hour, maybe two, which is a bit sad for 20 mins worth of plumbing. And mtb might be right, there just might be a hidden non return valve. Will go up to Northwich tomorrow and visit screwfix then have a look on Friday or Saturday.

 

If there is a non return valve then the service valve is largely redundant?  and draining the calorifier is difficult?????

 

................Dave

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Well mine hasn't got a NRV, it has an in line one between the cauliflower and the pump. I wasn't suggesting you use a bucket,how about a bit of hose into the shower tray or even this proper drain you are going to install 

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On Innisfree I installed the PRV on the calorifier cold inlet which vented to the outside via a skin fitting. All I had to do was connect an air pump to an open hot tap and then open PRV. Pressurised cal. then emptied overboard. 

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42 minutes ago, ditchcrawler said:

Well mine hasn't got a NRV, it has an in line one between the cauliflower and the pump. I wasn't suggesting you use a bucket,how about a bit of hose into the shower tray or even this proper drain you are going to install 

Hadn't thought of using the shower, its quite a long way but it might work.

 

.........Dave

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44 minutes ago, Mike the Boilerman said:

Rewinding to the beginning, I'm curious about how you know this isolator leaks when turned OFF. Why would you ever need to use it? Why not just turn the pump OFF and open the taps?

On the rare occasions when we leave the boat I turn this valve off so that if we did have a pipe burst from frost we would not dump the entire calorifier contents into the bilge. First noticed the leak when we went on holiday in January but it sorted itself out.   Have just broken into the cold water feed as I am re-routing/tidying some pipe runs and so closed the valve, the leak was quite bad. Its most serious with the valve closed and the supply still pressurised. Once I drop the pressure, or open the valve with pressure applied, it reduces to a gentle drip and then stops after an hour or so. I suspect it will get worse and go critical at the least convenient moment so plan to replace it in the next few days.

 

.................Dave

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MtB is advising that the tank will not empty itself when the  the leaky valve is disconnected from the tank but DMR is understandably nervous based on previous bad experience.  Is there a test method here where, instead of disconnecting the pipe on the tank side of the valve thus taking the risk, DMR leaves the valve in the "off" position and disconnects the (isolated) supply side first. Then the valve could opened to prove whether the tank will empty itself or not. If there's flow, simply shut the valve and work on plan B;  if there's no flow, the valve can be removed with confidence and replaced as per Mike's advice. 

 

Just a thought. :)

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