Calorifier confusion

[chubby]

Hello

 

Im fitting a new calorifier to my first boat . Im experiencing a few issues that are confusing me . Im no plumber and everything seems complicated .

Ive fitted a 55 litre vertical surecal twin coil tank. Cold feed is split to go in at the bottom AND into the top of tank . Hot comes out of the top of the tank two and i understand this is a mixer to regulate the temp of water going to hot taps. At the top of the tank another fitting is a pressure release valve . To my understanding it allows water to vent from the calorifier if the pressure inside gets too high as the water is heated .

I fitted the tank and all the fittings , pipes etc and turned onthe water pump to fill the calorifier . BUT theres water coming from the PRV already and ive not turned on the immersion or run the engine . Ive only added cold water to the tank .

Surecal say it may be a faulty pump operating at above 3 bar - the point at which the PRV vents . On the pump it says " 30 psi which apparently is approx 2 bar . A suggestion they make is to install an adjustable pressure gauge between pump and calorifier to establish actual pressure . Is this standard way of testing .

I thought it would be a straightforward swap but its a mare thats making my brain hurt and my wallets about to run dry .

Surecal advise i fit an expansion tank to my PRV for when my hot water is switched on ( more cash arrgghhh ) but that this tank will not solve the problem thats causing the PRV to flow now when its only cold .

Will i need to fit the adjustable gauge to ascertain if my pump is being too strong ?

If you understand my questions enough to help id be very grateful as im basically new to boats and new to plumbing and im all out of ideas .

Many thanks

[nicknorman]

If the PRV is discharging water, as you say the pressure in the system is too high or possibly its defective. Have you tried rotating the red knob on the PRV to re-seat it? As you mention, the pressure can get high either because the pump pressure is too high or when the calorifier is heated. In your case it looks like the pump pressure is too high for the PRV. Pump pressure regulators may not be that accurate and reliable so best to check the pressure. This is easy, assuming you have an accumulator in the cold feed after the pump somewhere. On top of the accumulator will be an air valve (like a car tyre valve). Assuming there was some air in the accumulator to start with, with the pump just cut out, the air pressure and the water pressure will be identical, therefore easy to measure using a car-type tyre pressure gauge. Just be careful because if you let all the air out of the accumulator, the gauge wont read correctly any more and the accumulator wont function as intended.

 

It might be worth checking the accumulator air pressure without the water pressurised - there are various threads about doing that on here, but basically it should be set to just below the pump cut-in pressure (you can measure that in a similar way). If you don't have an accumulator, that is not going to help.

 

You certainly don't want to put an expansion vessel on the PRV oulet - I think what Surecal will have meant is to put an expansion vessel on the hot water outlet, but that won't address the current problem (only helps if PRV blowing off due to heating)

Edited April 20, 2013 by nicknorman

[chubby]

Thanks nick

 

I find this all too confusing really . I dont understand the difference between accumulator tank and expansion tank !

I do have a Plastic tank above my calorifier . It was filled with antifreeze ( i think ) this is part of the central heating system from my eberspacher . It is connected to the pipes that return to the e erspacher after heating the rads .

The way i understood it when speaking to a very helpful man at Surecal was that the expansion tank goes on the PRV outlet .

Are you saying that ive understood him wrong and that it is fitted to the hot outlet pipe instead and this extra tank space will essentially make the PRV redundant because if pressure builds up inside the calotifier it will vent into the expansion tank connected to the hot outlet pipe instead ?

If so , ill still need to sort out why my PRV is flowing even when the water isn t heated . I stand no chance of doing as you suggest as its just too complicated for me and i may have to pay out for a pro to check it out .

Im stumped . I was very pleased that my first plumbing work didn t leak only to find the actual tanks dripping instead . Annoying really . Im sure its me tho and not the calorifier as i trust the quality of surecal .

Ill have to shell out for the adjustable pressure gauge in screwfix to check if the pressure going into the tank is too high and take it from there . The old system seems to have had no probs ( ive had boat 6 weeks ) , no expandion tanks , no PRVs etc so i dont get it !

Any more suggestions or advice please folks ?

Thanks

[nicknorman]

Thanks nick

 

I find this all too confusing really . I dont understand the difference between accumulator tank and expansion tank !

I do have a Plastic tank above my calorifier . It was filled with antifreeze ( i think ) this is part of the central heating system from my eberspacher . It is connected to the pipes that return to the e erspacher after heating the rads .

The way i understood it when speaking to a very helpful man at Surecal was that the expansion tank goes on the PRV outlet .

Are you saying that ive understood him wrong and that it is fitted to the hot outlet pipe instead and this extra tank space will essentially make the PRV redundant because if pressure builds up inside the calotifier it will vent into the expansion tank connected to the hot outlet pipe instead ?

If so , ill still need to sort out why my PRV is flowing even when the water isn t heated . I stand no chance of doing as you suggest as its just too complicated for me and i may have to pay out for a pro to check it out .

Im stumped . I was very pleased that my first plumbing work didn t leak only to find the actual tanks dripping instead . Annoying really . Im sure its me tho and not the calorifier as i trust the quality of surecal .

Ill have to shell out for the adjustable pressure gauge in screwfix to check if the pressure going into the tank is too high and take it from there . The old system seems to have had no probs ( ive had boat 6 weeks ) , no expandion tanks , no PRVs etc so i dont get it !

Any more suggestions or advice please folks ?

Thanks

In fact there are 3 things, are you are confused about 2 of them!

 

1) There would normally be an accumulator near the outlet of the water pump. Its purpose is to stop the pump cycling on and off rapidly if the water demand is less than the pump can deliver.

 

2) An Expansion vessel is a similar looking thing but its connected to the outlet from the calorifier to the hot taps. Its purpose is to limit pressure increase in the system when the water (and some air) in the calorifier heats up by providing somewhere for the excess volume to go, rather than triggering the PRV. FYI its typically pressurised to just below the pump cut out pressure (so different from the accumulator pressure which is cut-in pressure). In my opinion these are not really needed since all that happens is on every cycle of the calorifier from cold to hot, a bit of water leaks out (we are talking about a cupful) and provided the PRV outlet drains to somewhere sensible, is of no consequence. Some say that excercising the PRV is a good thing, rather than having it not move for years until there is an overpressure. Moral: This is not needed. If you do decide to fit one, it most certainly doesn't go on the PRV outlet, it goes on the hot water feed to the taps etc. I think you must have misunderstood Mr Surecal, or he is incompetant. Anyway it won't fix the problem as you describe it.

 

3) An Expansion tank. This is typically in the central heating circuit and or engine coolant system, so not part of the water system that supplies taps etc, only the part that provides heat to the calorifier. Typically a clear or white plastic tank, partially filled with anti-freeze solution. It may have a pressure cap on it, but this will open at a much lower pressure than the water pump will produce. Moral: This has no place in the plumbing from water tank via calorifier to taps etc.

 

To keep it simple, tell us what make / model of pump you have, whether you have an accumulator somewhere between the pump and the cold inlet to the calorifier, and we'll take it from there. I know it seems a little complicated but just putting a tyre pressure gauge on the accumulator air valve (once you have found it) is not too hard! Some systems don't have an accumulator but rather have a variable speed pump. That's why I ask for the make and model of pump.

 

Or give us a clue how the system behaves - when you turn on a cold tap, does the pump always cut in straight away or is there sometimes quite a delay, does the pump cycle on and off rapidly when the tap is partially open. Just describe the general behaviour. This will also give us a clue what sort of pump and whether there is an accumulator.

Edited April 20, 2013 by nicknorman

[Brin Morris]

Forget about the expansion tank for the moment as this has nothing to do with the problem. I have a 55 litre horizontal surcal and no expansion tank and it is not a problem. You could worry about this later if you get your pump cycling. The bit I am not sure about is the 2 cold feeds into the tank. althuogh i have a horizontal tank I have one cold feed into the tank and a hot water feed out. In other words one feed in and one out. There is a cold water feed that links to the mixer so you can adjust the temp of the hot water to the taps. Are you sure that the 2 cold water feeds into the tank are correct, the split of cold water maybe should be to the mixer and does not go into the calorifier. I would put a picture up but am not down at the boat until Tuesday.

Edited April 20, 2013 by Brin Morris

[chubby]

Hi guys ,

 

Ok . Firstly thanks for your patience with me . Im not the sharpest knife in the box when it comes to plumbing ..... And boats come to think of it . Its all a learning curve so thanks for your help .

 

Ok . Accumulator . Next to my pump there is a large white drum . To my understanding this is what ascertains pressure in the system and triggers the pump ? Pump is SHURFLO model unknown (im not on the boat ) . On it is

[chubby]

Oopps wrong button folk s, ill continue ....

On it is printed 30 psi . Thats all i can say for now . Am i correct in thinking that it is the white drum ( accumulator) that i would measure the pressure using a tyre gauge . I have a bicycle pump with a Pressure gauge - any good ?sorry .

 

Above my calorifier is a small plastic tank that before i fitted my new calorifier was just over half full of antifreeze .

 

Ive yet to refill this . Ive yet to top up my engine coolant . Ive yet to refill the rads . All these drained at least partially when i re routed pipes when replacing the calorifier .

 

The cold feed is T eed . One goes to the bottom of the calorifier where there is also a drain tap on the same brass fitting . The other goes to the top of the tank and goes into a mixer ( ?) to prevent overly hot water going to taps / shower - that at least is how i understand it .

 

The guy at surecal was very helpful so i expect i have misunderstood his recommendations . Am i correct then if i say that the expansion goes ( as you ve explained nicely ) on the hot outlet and if fitted nothing will exit the PRV ? If no expansion tank is fitted then any excess pressure WILL exit via the PRV ?

Therefore if i fit SOME sort of tank / bottle to my PRV using flexible hoses then ill be ok IF theres a problem ? To my understanding it would need to hold 10% of my calorifiers volume of 55 litres .?

 

Im really sorry folks for my perhaps dumb questions but as much as im struggling somewhat i really want to understand my own boats systems , otherwise i ll just remain in the dark as to how my home works !!

 

Thanks again for all your help - im immensly grateful

Cheers

[smileypete]

Im really sorry folks for my perhaps dumb questions but as much as im struggling somewhat i really want to understand my own boats systems , otherwise i ll just remain in the dark as to how my home works !!

 

Something that may help is reading the course notes on the TB Training website or better still go on one of the courses:

 

http://www.tb-training.co.uk/

 

cheers, Pete.

~smpt~

[nicknorman]

Ok . Accumulator . Next to my pump there is a large white drum . To my understanding this is what ascertains pressure in the system and triggers the pump ? Pump is SHURFLO model unknown (im not on the boat ) . On it is

No this is probably the accumulator. "large" is a relative term but larger than the pump and with no wires? Its the accumulator. Much smaller than the pump, and having wires connecting to the pump, its a pressure switch, although typically these are incorporated into the pump.

 

Lets assume its the accumulator. No, the accumulator doesn't ascertain the system pressure and trigger the pump, that is the pressure switch. The accumulator is just a means of storing water under pressure so that when you open a tap, water can flow out of the pressurised accumulator for a while until the pressure drops to the point the pressure switch cuts the pump in. Then the pump provides not only the flow to the tap, but typically some extra flow to put back that water into the accumulator. Once the system pressure has built up the pump cuts out again for a while. So what you see at the tap is a reasonably constant flow even though the pump is sometimes running, sometimes not. Without the accumulator, the pump would be cutting in and out several times a second.

[nicknorman]

Oopps wrong button folk s, ill continue ....

On it is printed 30 psi . Thats all i can say for now . Am i correct in thinking that it is the white drum ( accumulator) that i would measure the pressure using a tyre gauge . I have a bicycle pump with a Pressure gauge - any good ?sorry .

 

Above my calorifier is a small plastic tank that before i fitted my new calorifier was just over half full of antifreeze .

 

Ive yet to refill this . Ive yet to top up my engine coolant . Ive yet to refill the rads . All these drained at least partially when i re routed pipes when replacing the calorifier .

 

The cold feed is T eed . One goes to the bottom of the calorifier where there is also a drain tap on the same brass fitting . The other goes to the top of the tank and goes into a mixer ( ?) to prevent overly hot water going to taps / shower - that at least is how i understand it .

 

The guy at surecal was very helpful so i expect i have misunderstood his recommendations . Am i correct then if i say that the expansion goes ( as you ve explained nicely ) on the hot outlet and if fitted nothing will exit the PRV ? If no expansion tank is fitted then any excess pressure WILL exit via the PRV ?

Therefore if i fit SOME sort of tank / bottle to my PRV using flexible hoses then ill be ok IF theres a problem ? To my understanding it would need to hold 10% of my calorifiers volume of 55 litres .?

 

Im really sorry folks for my perhaps dumb questions but as much as im struggling somewhat i really want to understand my own boats systems , otherwise i ll just remain in the dark as to how my home works !!

 

Thanks again for all your help - im immensly grateful

Cheers

OK so it says 30psi but something is wrong, so a likely cause is that the pump is actually cutting out at a higher pressure. You should find a tyre-type valve on the accumulator, sometimes under a flat screw-on cap at the top if not immediately visible. You should be able to use you bicycle pump gauge to get a rough idea, but a proper tyre pressure gauge of the type where a plunger slides out (cheap from halfords etc) would be better.

 

Lets skip the whole header tank / antifreeze bit because that's not relevant to your problem.

 

I have to agree with Brin, it seems odd to have 2 cold feeds into the calorifier. Normally there is only 1 cold feed at the bottom. Sometimes a mixer is fitted external to the calorifier that requires another cold feed to mix with the hot outlet, but you imply that both cold feeds go actually into the calorifier. Strange! Maybe you could post a link to the exact calorifier that you have fitted?

 

If you fit an expansion vessel to the hot outlet and its the correct size, you would not expect to get any discharge from the PRV once your current problem is sorted. Remember that an expansion vessel will not fix a problem that exists when the calorifier is cold. However, sometimes PRVs leak and anyway the whole point is to cater for the case where eg the pump pressure switch sticks and the pump continues to run, so its important to route the PRV outlet to somewhere that can deal with a discharge. Typically the propellor stern gland area, where there will be a bilge pump, is a good place, or overboard through a skin fitting is even better. If you just fit a bottle, it can fill up and then overflow. Even if only a small discharge occurs, when the calorifier cools it will not be sucked back in again so the level in the bottle will just fill and fill until it overflows. In this respect it is a different animal from an expansion tank on the CH / engine coolant circuit, where there is easy flow in and out of the bottle.

 

Phew. Anyway, plan of action is to check the system pressure with the pump on and the PRV problem manifesting itself. If the pressure is much over 30 psi, there is a problem with the pump pressure switch. If its 30psi or less, there is a problem with the PRV. Simples, then take it from there!

 

ETA a photo is worth a thousand words (two thousand of mine!) so if you are still struggling, try to post some photos of the equipment.

Edited April 20, 2013 by nicknorman

[chubby]

Nicknorman

 

Youre a legend . Cheers again .

 

Ok the cold feed is split . BUT one is cold feed at the bottom. The other is into a mixer bolted onto the top . To my understanding cold water only flows thru this mixer fitting if the temp of the hot water flowing out of the calorifier is too high.

 

I will pick up the tyre pressure gauge today if i can and check the pressure . When i bought the boat there was a spare water pump under the bed . It says 30 psi too and is manufactured by Whale .

 

So my first job will be to check the pressure when i get back to my boat tonight .

Cheers again

[nicknorman]

Ok the cold feed is split . BUT one is cold feed at the bottom. The other is into a mixer bolted onto the top . To my understanding cold water only flows thru this mixer fitting if the temp of the hot water flowing out of the calorifier is too high.

 

Ok that sounds "normal"!

[ditchcrawler]

Its always possible that the Relief Valve is faulty

[nicknorman]

Its always possible that the Relief Valve is faulty

Yes definitely! Although the pump is perhaps a more likely culprit.

 

I am just installing our new bathroom in the house, got a fancy thermostatic shower valve ( £200+) but found after I installed it, plumbed it, tiled it that it didn't let any hot water out! Fortunately its an external/ exposed type so easy to remove without trashing the tiling, but to cut a long story short, the thermostatic cartridge had a broken piece inside it. After a bit of debate on the phone ( him saying "try this..." and me saying "Yup, already done that") they sent me a new one which works perfectly.

 

So of course the moral is that just because its new doesn't mean it works properly!

Edited April 21, 2013 by nicknorman

[ditchcrawler]

Yes definitely! Although the pump is perhaps a more likely culprit.

 

I am just installing our new bathroom in the house, got a fancy thermostatic shower valve ( £200+) but found after I installed it, plumbed it, tiled it that it didn't let any hot water out! Fortunately its an external/ exposed type so easy to remove without trashing the tiling, but to cut a long story short, the thermostatic cartridge had a broken piece inside it. After a bit of debate on the phone ( him saying "try this..." and me saying "Yup, already done that") they sent me a new one which works perfectly.

 

So of course the moral is that just because its new doesn't mean it works properly!

I was working on the basis that his pumped worked before

[chubby]

Hello .

 

Thanks again to you all for your help on my calorifier problem . I bought the tyre pressure gauge and the pressure read 42 psi , which is higher than the 30 psi printed on the pump .

Myself and a mate have fitted an adjustable pressure gauge between the accumulator and the calorifier and it seems fine now , so hopefully the problem is solved . At some point soon ill have to fit an expansion tank on the hot feed from the calorifier to as i cannot run a pipe from the pressure release valve to my engine bilge as it means drilling thru the steel bulkhead and i dont really like the idea of that . Ive yet to turn on the hot water so when i do in the next day or two i shall watch it like a paranoid hawk for a while to see if the PRV on the calorifier is ok .

Thanks again for all your help and a special thanks to nicknorman as you ve been v patient and generous with your knowledge and your explanations were very clear and easy to follow - even for a dunce like me .

 

Cheers again

[jelunga]

Hello .

 

Thanks again to you all for your help on my calorifier problem . I bought the tyre pressure gauge and the pressure read 42 psi , which is higher than the 30 psi printed on the pump .

Myself and a mate have fitted an adjustable pressure gauge between the accumulator and the calorifier and it seems fine now , so hopefully the problem is solved . At some point soon ill have to fit an expansion tank on the hot feed from the calorifier to as i cannot run a pipe from the pressure release valve to my engine bilge as it means drilling thru the steel bulkhead and i dont really like the idea of that . Ive yet to turn on the hot water so when i do in the next day or two i shall watch it like a paranoid hawk for a while to see if the PRV on the calorifier is ok .

Thanks again for all your help and a special thanks to nicknorman as you ve been v patient and generous with your knowledge and your explanations were very clear and easy to follow - even for a dunce like me .

 

Cheers again

If your tank is fitted anywhere near your bathroom, you could Tee in the PRV outlet to the washbasin or shower Overboard pipe before the hull fitting. Ours is onto the shower outlet and seems ok although I do not think the PRV has triggered.

In respect of the pressure, measure the expansion tank pressure with your tyre gauge just after water pump has cut out. Then turn pump off, open all taps and measure pressure on the expansion tank when all water has stopped flowing. 2nd pressure should be quite low at maybe 10-15 psi.

Edited April 24, 2013 by jelunga

[nicknorman]

Hello .

Thanks again to you all for your help on my calorifier problem . I bought the tyre pressure gauge and the pressure read 42 psi , which is higher than the 30 psi printed on the pump .

Myself and a mate have fitted an adjustable pressure gauge between the accumulator and the calorifier and it seems fine now , so hopefully the problem is solved . At some point soon ill have to fit an expansion tank on the hot feed from the calorifier to as i cannot run a pipe from the pressure release valve to my engine bilge as it means drilling thru the steel bulkhead and i dont really like the idea of that . Ive yet to turn on the hot water so when i do in the next day or two i shall watch it like a paranoid hawk for a while to see if the PRV on the calorifier is ok .

Thanks again for all your help and a special thanks to nicknorman as you ve been v patient and generous with your knowledge and your explanations were very clear and easy to follow - even for a dunce like me .

Cheers again

Glad to be of help. Please bear in mind that your PRV might start to discharge sometime in the future, years hence when you have forgotten about it, due to pressure switch sticking or a bit of lime scale on the PRV. Therefore you really need to have the PRV outlet going somewhere safe. Better to spend a bit of time sorting it now, than having to clear up a mess in the future at (inevitably) a really inconvenient time! As has been suggested, it could be Td into an existing drain or given its own skin fitting to discharge over the side.