Water Pressure Regulator

[PeterDHS]

A few years back my water pump failed and because of a history of poor and unreliable showers I persuaded myself to buy a higher powered Par Max 2.9 bar pump. Bad thinking. I then had to upgrade the PRV to 3 bar and even then when the engine is worked hard I have a constant weep from the PRV. Also I have concerns over the pressure on the calorifier and possible damage.

ROOF details Model (1).pdf.

(sorry, can't quite work out the PDF attachment thing).

Anyway the issue is i now have a dial/adjustable pressure regulator which may be the answer if i knew where to fit it.

if i fit it between the pump and the accumulator then the accumulator won't stop the pump cycling. If i fit it downstream of the accumulator the pump shouldnt cycle but the accumulator won't provide any expansion, so i may need another 'expansion' tank near the calorifier. Maybe I'm confused about the accumulator/expansion function.

So where to put the regulator ? And would I need another expansion tank ?

 

Peter

ps- the shower mixer was replaced and is now not an issue.

[dmr]

The pump should cut out at 1.7 bar. A 3.0 bar PRV is pretty standard so should be ok.

Are you sure that you have not fitted a high pressure pump by mistake?

 

You can get a fairly cheap pressure gauge from a plumbers merchant. If you connect this to the hot water outlet from the calorifier you will rapidly get to see what is going on.

 

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

[MtB]

A few years back my water pump failed and because of a history of poor and unreliable showers I persuaded myself to buy a higher powered Par Max 2.9 bar pump. Bad thinking. I then had to upgrade the PRV to 3 bar and even then when the engine is worked hard I have a constant weep from the PRV. Also I have concerns over the pressure on the calorifier and possible damage.

ROOF details Model (1).pdf.

(sorry, can't quite work out the PDF attachment thing).

Anyway the issue is i now have a dial/adjustable pressure regulator which may be the answer if i knew where to fit it.

if i fit it between the pump and the accumulator then the accumulator won't stop the pump cycling. If i fit it downstream of the accumulator the pump shouldnt cycle but the accumulator won't provide any expansion, so i may need another 'expansion' tank near the calorifier. Maybe I'm confused about the accumulator/expansion function.

So where to put the regulator ? And would I need another expansion tank ?

 

Peter

ps- the shower mixer was replaced and is now not an issue.

 

 

 

My eyes glazed over after reading this for the third time...

 

My advice is start by reading the installation instructions for the calorifier. This will tell you what accumulator(s) are needed, where to put them and what pressure to run the system at.

[alan_fincher]

The pump should cut out at 1.7 bar.

 

Surely a 2.9 bar pump (as stated) should cut out at 2.9 bar?

 

That's not a lot of margin with a 3.0 bar PRV.

 

From the descriptions the OP seems to currently have a cold water accumulator, but no separate hot water expansion vessel.

 

They don't say if there is a non return valve (NRV) in the supply to the calorifier, (and indeed they may not even know they have - Surejust/Surecal ones incorporate one in the calorifier plumbing in a fairly non obvious way.

 

If there is a NRV anywhere, then the accumulator cannot perform the function of an expansion vessel (EV) as the water in the calorifier heats.

 

To me it sounds this is possible, which means the PRV has to dribble, as there is no where else for the expanded water to go.

 

If there is an NRV, adding an EV to the calorifier side of the plumbing may well stop the PRV leak, although 3.0 bar still sounds very close to 2.9 bar to me, so if either of these figures is inaccurate, it might still leak, I think. If the pump has a 2.9 bar cut out, I think a 4 bar PRV might be a better option, provided the calorifier is OK at 4 bar. (I seem to recall Surecal have at some stage upped the PRV they fit to their pre-plumbed calorifies from 3 bar to 4 bar - the one I had was 3 bar, but latest specs say 4 bar - presumably to give margin with the higher pressure pumps.).

Edited April 21, 2016 by alan_fincher

[Phil Ambrose]

Simple answer would be to put the pressure regulating valve between the pump and the calorifier. I'm a bit confused, I thought 3 bar is the norm for PRVs, and just a thought, why not turn down the pressure on your pump if that's possible

The fact that your PRV dribbles when running indicates that all is well because as the water heats up it expands and consequently dumps overboard, if a tap is run and cold water introduced to the calorifier the whole process starts again. You should also check the pressure of your expansion tank

Phil

[MtB]

Simple answer would be to put the pressure regulating valve between the pump and the calorifier. I'm a bit confused, I thought 3 bar is the norm for PRVs, and just a thought, why not turn down the pressure on your pump if that's possible

The fact that your PRV dribbles when running indicates that all is well because as the water heats up it expands and consequently dumps overboard, if a tap is run and cold water introduced to the calorifier the whole process starts again. You should also check the pressure of your expansion tank

Phil

 

 

Eh?!

 

A PRV only discharges under fault conditions. Something is badly wrong if a safety device such as a PRV is stepping in and operating.

[dor]

I've got a Parmax 2.9. In my experience it is the best pump I have had. No problem with a 3 bar PRV providing you have set the plumbing up correcty, i.e. have an appropriate accumulator/pressure vessel to take the normal expansion of the water as it heats up. you shouldn't have any leakage through the PRV. Proper marine calorifiers (as opposed to domestic hot water tanks) should be rated at at least 5 bar.

[MtB]

I've got a Parmax 2.9. In my experience it is the best pump I have had. No problem with a 3 bar PRV providing you have set the plumbing up correcty, i.e. have an appropriate accumulator/pressure vessel to take the normal expansion of the water as it heats up. you shouldn't have any leakage through the PRV. Proper marine calorifiers (as opposed to domestic hot water tanks) should be rated at at least 5 bar.

 

 

What do you mean by 'rated at', exactly please?

[dmr]

 

Surely a 2.9 bar pump (as stated) should cut out at 2.9 bar?

 

That's not a lot of margin with a 3.0 bar PRV.

 

From the descriptions the OP seems to currently have a cold water accumulator, but no separate hot water expansion vessel.

 

They don't say if there is a non return valve (NRV) in the supply to the calorifier, (and indeed they may not even know they have - Surejust/Surecal ones incorporate one in the calorifier plumbing in a fairly non obvious way.

 

If there is a NRV anywhere, then the accumulator cannot perform the function of an expansion vessel (EV) as the water in the calorifier heats.

 

To me it sounds this is possible, which means the PRV has to dribble, as there is no where else for the expanded water to go.

 

If there is an NRV, adding an EV to the calorifier side of the plumbing may well stop the PRV leak, although 3.0 bar still sounds very close to 2.9 bar to me, so if either of these figures is inaccurate, it might still leak, I think. If the pump has a 2.9 bar cut out, I think a 4 bar PRV might be a better option, provided the calorifier is OK at 4 bar. (I seem to recall Surecal have at some stage upped the PRV they fit to their pre-plumbed calorifies from 3 bar to 4 bar - the one I had was 3 bar, but latest specs say 4 bar - presumably to give margin with the higher pressure pumps.).

 

I think the 2.9 refers to flow rate rather than pressure.

 

If the PRV leaks when the engine is running it does sound like a non return valve allowing pressure buildup in the calorifier. A second accumulator could be the answer....or getting rid of the non return valve.

 

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

[Phil Ambrose]

 

 

What do you mean by 'rated at', exactly please?

Manufactured to withstand at least 5 bar pressure I believe.

Phil

[alan_fincher]

 

I think the 2.9 refers to flow rate rather than pressure.

 

Now, I check, doesn't immediately seem to relate to either - I was trusting the OP's "2.9 bar" which it seems is incorrect, and your 1.7 bar is right, now I look.

 

However open flow rate quotes at 11 litres per minute or 2.4 gallons per minute.........

 

Hang on - I've just realised it must be 2.9 US gallons per minute - hardly informative when sold in the UK.

 

So a 3.0 bar PRV should be fine. I therefore suspect there is an NRV present, and no hot water expansion vessel.

 

OP - is the calorifier a blue lagged Surecal/Surejust one, please?

[MtB]

Manufactured to withstand at least 5 bar pressure I believe.

Phil

 

 

Ok I'll rephrase. What so you mean by that?

 

1) Pressure tested in the factory to 5 bar with a safety factor of 2, so intended for use at a max of 2.5 bar? Or...

 

2) Designed to run at 5 bar on a day-by-day basis and pressure tested at the factory to 10 bar, assuming a safety factor of 2?

[PeterDHS]

Hi guys, OP here and just back from the boat. Thanks for your inputs so far which my brain is trying to absorb.

Better info in the meantime-

Calorifier is 800x300 Albion Marine labelled 3 bar max, looks really heavy duty but no obvious NRV here or anywhere on the system.Albion is no longer trading. I obviously don't want the pressure plus expansion to exceed the 3 bar limit of the caloifier or the PRV.

Accumulator is 5 litre set at just over 1 bar (13/14 psi), although difficult to set or read accurately.

The ParMax 2.9 pump cuts in at 1.4 bar and out at 2.7 bar (40 psi) and the blurb says 'no need for an accumulator' (?). It is not adjustable.

 

So my guess is that everything is theoretically fine but working on the upper pressure limits, until heat expansion overtops the PRV which is not ideal.

 

I'm thinking my best option may be to put a pressure regulator where the accumulator sits (next to the pump) and move the accumulator near to the calorifier to soak up the expansion ?. The pressure regulator is of course a NRV.

 

Peter

[bizzard]

Hi guys, OP here and just back from the boat. Thanks for your inputs so far which my brain is trying to absorb.

Better info in the meantime-

Calorifier is 800x300 Albion Marine labelled 3 bar max, looks really heavy duty but no obvious NRV here or anywhere on the system.Albion is no longer trading. I obviously don't want the pressure plus expansion to exceed the 3 bar limit of the caloifier or the PRV.

Accumulator is 5 litre set at just over 1 bar (13/14 psi), although difficult to set or read accurately.

The ParMax 2.9 pump cuts in at 1.4 bar and out at 2.7 bar (40 psi) and the blurb says 'no need for an accumulator' (?). It is not adjustable.

 

So my guess is that everything is theoretically fine but working on the upper pressure limits, until heat expansion overtops the PRV which is not ideal.

 

I'm thinking my best option may be to put a pressure regulator where the accumulator sits (next to the pump) and move the accumulator near to the calorifier to soak up the expansion ?. The pressure regulator is of course a NRV.

 

Peter

Is the calorifier a vertical or horizontal one and whereabouts on it is the PRV. Ideally it needs to be at the highest possible position on it, because I've found that calorifiers seem to trap a little air at the very top which cushions the PRV and stops it popping off so easily.

[dmr]

Hi guys, OP here and just back from the boat. Thanks for your inputs so far which my brain is trying to absorb.

Better info in the meantime-

Calorifier is 800x300 Albion Marine labelled 3 bar max, looks really heavy duty but no obvious NRV here or anywhere on the system.Albion is no longer trading. I obviously don't want the pressure plus expansion to exceed the 3 bar limit of the caloifier or the PRV.

Accumulator is 5 litre set at just over 1 bar (13/14 psi), although difficult to set or read accurately.

The ParMax 2.9 pump cuts in at 1.4 bar and out at 2.7 bar (40 psi) and the blurb says 'no need for an accumulator' (?). It is not adjustable.

 

So my guess is that everything is theoretically fine but working on the upper pressure limits, until heat expansion overtops the PRV which is not ideal.

 

I'm thinking my best option may be to put a pressure regulator where the accumulator sits (next to the pump) and move the accumulator near to the calorifier to soak up the expansion ?. The pressure regulator is of course a NRV.

 

Peter

Mikes yer man here, I don't have any hands on experience of this.

How is this pressure regulator going to work?

It must open and close somehow, so.... the engine heats the calorifier and the water expands and increases the pressure. This expanded water needs to go somewhere, what does the regulator do? how does it help?

If there is a non return valve then take it away, maybe its just not obvious and hiding somewhere??

 

If the PRV is a non return valve then its not certain to help. It will lower the pressure in the calorifier and hot water system (which might degrade your shower) and so might be enough to prevent the calorifier getting up to 3 bar....but then again it might not.

 

Are you sure the accumulator is actually working......when you turn the taps on how long before the pump kicks in????

 

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

[smileypete]

My eyes glazed over after reading this for the third time...

 

My advice is start by reading the installation instructions for the calorifier. This will tell you what accumulator(s) are needed, where to put them and what pressure to run the system at.

 

No need to patronise the OP, most of what they need to know was covered in a topic a mere couple of days ago, which you surely must have seen:

 

http://www.canalworld.net/forums/index.php?showtopic=84118&page=2#entry1807138

 

 

MtBs signature may be somewhat ironic...

 

cheers, Pete.

~smpt~

[PeterDHS]

Bizzard- the calorifier is vertical near the rear of the boat and the PRV sits on top.

Dave- I think the pressure regulators are spring loaded things, very much like a PRV really, so the pump might cut out at 2.7 bar but anything downstream of the regulator would be at 1.5 bar, or whatever it is set at. The pump says it does not need an accumulator, although I guess it might cycle less with one.

 

Pete the OP

[PeterDHS]

Thanks SmileyPete !!!

That diagram seems to answer the question, ie it shows a reducer and an expansion tank, much as I proposed to do it. Excellent work and thankyou.

Pete the OP

 

MtB- sorry you glazed over, not my intention.

[alan_fincher]

The ParMax 2.9 pump cuts in at 1.4 bar and out at 2.7 bar (40 psi)

 

Where are you getting that information from, please?

 

It seems there a different models all branded ParMax 2.9, and they are available with different pressures. However most examples being sold for marine use, such as here say......

 

PRESSURE SWITCH - cuts in at 1.0bar (15psi) - cuts out at 1.7bar (25psi)

 

I believe the pumps on our boat are the ParMax, (but would need to check), and these lower figures sound much more like what I measured there.

 

So do you actually have firm evidence that your particular pump cuts out at 2.7 bar rather than (I would suggest more usual) 1.7 bar?

 

Note that not needing an accumulator, is not the same as not needing an expansion vessel. If there were a non return valve present anywhere on the feed to the calorifier, (even if you have not found it!), then an accumulator can not serve the function of an expansion vessel, and expansion of water when heating can only force it out the PRV, or split the cylinder, (water not being compressible).

 

My concern would be that if the pump genuinely puts out a nominal 2.7 bar, and the calorifier is only good for 3 bar, that is not a great deal of safety margin, and you are of course relying on a PRV rated at 3 bar to open at that pressure, and no higher.

[Guest User]

 

<snip> If there is a NRV anywhere, then the accumulator cannot perform the function of an expansion vessel (EV) as the water in the calorifier heats. <snip>

<snip> No problem with a 3 bar PRV providing you have set the plumbing up correcty, i.e. have an appropriate accumulator/pressure vessel to take the normal expansion of the water as it heats up. <snip>

 

 

<snip> If the PRV leaks when the engine is running it does sound like a non return valve allowing pressure buildup in the calorifier. A second accumulator could be the answer....or getting rid of the non return valve <snip>

 

<snip> I'm thinking my best option may be to put a pressure regulator where the accumulator sits (next to the pump) and move the accumulator near to the calorifier to soak up the expansion ?. The pressure regulator is of course a NRV <snip>

 

 

<snip> Note that not needing an accumulator, is not the same as not needing an expansion vessel. If there were a non return valve present anywhere on the feed to the calorifier, (even if you have not found it!), then an accumulator can not serve the function of an expansion vessel, and expansion of water when heating can only force it out the PRV, or split the cylinder, (water not being compressible) <snip>

 

Hi,

 

When I first bought my boat it had a similar leaky PRV problem as the OP describes (and a very similar layout as in the diagram), nor could I find a non-return valve either. In the end I fitted a second accumulator to the hot water outlet from the calorifier, to act as an expansion vessel. It's sited pretty much directly on top of my vertically orientated caloifier. It solved the problem.

 

LCx

Edited April 23, 2016 by Lady Cassandra

[MtB]

 

No need to patronise the OP, most of what they need to know was covered in a topic a mere couple of days ago, which you surely must have seen:

 

http://www.canalworld.net/forums/index.php?showtopic=84118&page=2#entry1807138

 

 

MtBs signature may be somewhat ironic...

 

cheers, Pete.

~smpt~

 

 

I wasn't tryimng to patronise the OP, just pointing out that the answers he seeks can usually be found in the instruction book for the calorifier, because people often don't realise or remember there IS one!

 

One point still not mentioned so far (other than by me), and not picked up upon given subsequent comments, is that the contrary to the diagram above, the NRV on a calorifier is sometimes located inside the actual cold fill pipe connection fitting brazed onto the base of the calorifier. In which case the vessel labelled 'expansion tank' in the diagram above needs to be fitted on the hot outlet, not the cold inlet.

 

One way to check for presence of one there (other than by reading the instructions booklet) is to drain the system then disconnect the cold fill pipe and look into the pipe connection on the calorifier with a torch. Another way is to turn the pump OFF, open the cold taps to relieve the cold circuit pressure, then loosen or disconnect the cold fill pipe from the base of the calorifier. If there is a NRV fitted inside the connector, little or no water will spill out. If there no NRV inside, the water in the calorifier will start glooping out (technical term) all over the place.

 

 

 

(Edits to improve clarity.)

Edited April 23, 2016 by Mike the Boilerman

[Chewbacka]

If you want to reduce the pressure and the pump pressure switch will not adjust, why not use a 'remote' pressure switch to cut the power to the pump?

Something like this

http://www.ebay.co.uk/itm/Garden-Water-Jet-Pump-Pressure-Switch-Control-Double-Pole-Silver-Contacts-G1-4-/272104589114?hash=item3f5ab2873a

[PeterDHS]

Thanks MtB,I was guessing the expansion tank would be better on the hot pipe, good to have it confirmed with clarity. As said the calorifier is an 'Albion', no paperwork, and the company no longer exists.

Chewbacka,good thinking ! Not much info on the website but I have concerns about over-riding the pump cutout and it looks like a 240 v fitting to me (what do I know).

Thanks both

Pete the OP

[MtB]

Thanks MtB,I was guessing the expansion tank would be better on the hot pipe, good to have it confirmed with clarity. As said the calorifier is an 'Albion', no paperwork, and the company no longer exists.

Chewbacka,good thinking ! Not much info on the website but I have concerns about over-riding the pump cutout and it looks like a 240 v fitting to me (what do I know).

Thanks both

Pete the OP

 

 

There is a drawback to it being on the hot pipe, so its better on the cold supply provided there is no NVV hidden in the cylinder cold fill connection. On the hot pipe, when you turn a hot tap ON the system pressure falls a little, and the expansion vessel shoots half a litre of cold water into the hot pipe which needs to be drawn off before hot water arrives at the hot tap. This waste of water is more significant in a boat than in a house.

[ditchcrawler]

Thanks MtB,I was guessing the expansion tank would be better on the hot pipe, good to have it confirmed with clarity. As said the calorifier is an 'Albion', no paperwork, and the company no longer exists.

Chewbacka,good thinking ! Not much info on the website but I have concerns about over-riding the pump cutout and it looks like a 240 v fitting to me (what do I know).

Thanks both

Pete the OP

You wont be over riding the pump switch as you will be interrupting the supply to the pump before it cuts out, Just like switching the breaker off when the pressure reaches what you want,If the switch failed to operate the pump switch would cut its self off as normal. Yes its 240 volt but that in its self is not a reason for not using it on 12 volts DC