Jump to content

"outside the box" thinkers only please!!!


Featured Posts

19 minutes ago, Tash and Bex said:

a calorifier is running at 25psi in most cases, which is around the same pressure as a non vented domestic system. the issue really comes if the prv fails, they don't half go boom if they boil up....

 

PRVs tend to fail safe, ie they open at a lower pressure than design. Dirt builds up around the valve opening and prevents a reliable seal. To fail closed, the spring would need to become jammed or some other moving part seize. I can't see that happening if its regularly used. But if it does, normally a plastic pipe would either split or a joint would fail, so it would leak and drop the pressure. There may be a bit of steam/condensation, and an amount of hot water, but nothing more dangerous than that. I'd not worry about safety aspects of a calorifier failing, just the inconvenience/cleanup factor.

 

I think we're on the same page re: likely pressures though. Typically a PRV is 3 bar; and a 12V water pump typically has a 25-30psi cutout.

 

14psi = 1bar (approx)

Edited by Paul C
Link to comment
Share on other sites

4 minutes ago, Paul C said:

PRVs tend to fail safe, ie they open at a lower pressure than design. Dirt builds up around the valve opening and prevents a reliable seal. To fail closed, the spring would need to become jammed or some other moving part seize. I can't see that happening if its regularly used. But if it does, normally a plastic pipe would either split or a joint would fail, so it would leak and drop the pressure. There may be a bit of steam/condensation, and an amount of hot water, but nothing more dangerous than that. I'd not worry about safety aspects of a calorifier saving, just the inconvenience/cleanup factor.

generally yes, a split tank is the most dramatic outcome, and I have no concerns whatsoever about pressurised HW systems!

Link to comment
Share on other sites

8 minutes ago, Tash and Bex said:

please expand?

 

Well a domestic vented tank has a pressure rating of 50 ft head of water, that is only about 21 psi  so if you used one of those on your pumped system you would need to drop the pressure by 4 psi and also find a pressure relief valve to suit. Maybe something like one of these would be better/safer https://www.telford-group.com/tempest-stainless.html

Link to comment
Share on other sites

Well the obvious solution is to fit a big standard MEGAflo. (Google it) heated by whatever method you currently heat your calorifier. 

 

These are household mains pressure hot water cylinders, topographically identical to a calorifier but big enough to fill a bath. 

 

 

Edited by Mike the Boilerman
  • Greenie 1
Link to comment
Share on other sites

35 minutes ago, Paul C said:

PRVs tend to fail safe, ie they open at a lower pressure than design. Dirt builds up around the valve opening and prevents a reliable seal. To fail closed, the spring would need to become jammed or some other moving part seize. I can't see that happening if its regularly used. But if it does, normally a plastic pipe would either split or a joint would fail, so it would leak and drop the pressure. There may be a bit of steam/condensation, and an amount of hot water, but nothing more dangerous than that. I'd not worry about safety aspects of a calorifier failing, just the inconvenience/cleanup factor.

 

I think we're on the same page re: likely pressures though. Typically a PRV is 3 bar; and a 12V water pump typically has a 25-30psi cutout.

 

14psi = 1bar (approx)

I have had a spit cauliflower, expansion vessel and prv failed it was a right mess! Newark cylinders repaired it for me. The pressure vessel and prv are now in cupboard with the cauliflower

Edited by peterboat
Link to comment
Share on other sites

43 minutes ago, ditchcrawler said:

Well a domestic vented tank has a pressure rating of 50 ft head of water, that is only about 21 psi  so if you used one of those on your pumped system you would need to drop the pressure by 4 psi and also find a pressure relief valve to suit. Maybe something like one of these would be better/safer https://www.telford-group.com/tempest-stainless.html

a vented tank is at atmospheric pressure, it's vented!

 

Link to comment
Share on other sites

31 minutes ago, Mike the Boilerman said:

Well the obvious solution is to fit a big standard MEGAflo. (Google it) heated by whatever method you currently heat your calorifier. 

 

These are household mains pressure hot water cylinders, topographically identical to a calorifier but big enough to fill a bath. 

 

 

yes, that would be a solution, however I would struggle to site it, hence it would need to be horizontal and even then would be inconvenient.

 

also, if I have a system running the same capacity of storage as the bath it would only ever need to get to bath water temperature, a domestic unvented calorifier seems a bit overkill.....Now if I had a widebeam it would be a different story

Link to comment
Share on other sites

Tinkin outside da box-boat.  Mount bath upon bricks on towpath. Fill with canal water. Light a fire of sticks beneath it. Wait one hour precisely to heat up. Jump in with toy boat or duck.:closedeyes:

Edited by bizzard
  • Haha 1
Link to comment
Share on other sites

27 minutes ago, Tash and Bex said:

yes, that would be a solution, however I would struggle to site it, hence it would need to be horizontal and even then would be inconvenient.

 

also, if I have a system running the same capacity of storage as the bath it would only ever need to get to bath water temperature, a domestic unvented calorifier seems a bit overkill.....Now if I had a widebeam it would be a different story

 

Get one made then to whatever size and format you want it to be then. Won’t cost much more than an off-the-shelf one. 

 

Domestic unvented cylinders start at about 80 litres. Think out of the box!! 

 

Link to comment
Share on other sites

1 minute ago, Mike the Boilerman said:

 

Get one made then to whatever size and format you want it to be then. Won’t cost much more than an off-the-shelf one. 

 

Domestic unvented cylinders start at about 80 litres. Think out of the box!! 

 

lol, you consider that using a hot water cylinder as a.....hot water cylinder represents out of the box thinking?

 

domestic unvented cylinders aka calorifiers seems rather firmly in the box to me, but I appreciate your suggestion

Link to comment
Share on other sites

Just now, Paul C said:

I'm not sure you're thinking outside the box; you just want someone to agree that your idea of an unvented plastic tank, raised to tepid temperature, will be okay.

well, raised to bathwater temperature, but yes, essentially, the advantages of such a system outweigh any other choices as far as I can tell

Link to comment
Share on other sites

1 minute ago, stegra said:

Might be possible to get a square hot water tank custom made to fit in the space where you originally planned. Google brought up this company that supplies bespoke tanks in all shapes and sizes:

 

http://www.gasapplianceguide.co.uk/Bespoke hot water cylinders.htm

thanks, I will look into it

Link to comment
Share on other sites

Just now, Paul C said:

"be aware, water is more often than not stored in a cylindrical vessel for good reason."

yes, in a pressurised system cylinders have a much better resistance to splitting and deforming, but I would contest your supposition that water is more often stored in cylinders as I live on a rather long stretch of canal which seems to be rather reasonable at storing water, domestic supply tank is frankly some kind of crazy polygon and my fish tank is a cube.

 

I think the "good reason" you allude to is that it's much much cheaper to make cylindrical pressure vessels than any other shape. 

Link to comment
Share on other sites

 

1 hour ago, ditchcrawler said:

Well a domestic vented tank has a pressure rating of 50 ft head of water, that is only about 21 psi 

 

55 minutes ago, Tash and Bex said:

a vented tank is at atmospheric pressure, it's vented!

 

Not necessarily!

A domestic vented tank could be fitted 50 feet lower than the header tank which feeds it, on which case the pressure in the tank would be a 50 ft head above atmospheric pressure.

Link to comment
Share on other sites

42 minutes ago, bizzard said:

Tinkin outside da box-boat.  Mount bath upon bricks on towpath. Fill with canal water. Light a fire of sticks beneath it. Wait one hour precisely to heat up. Jump in with toy boat or duck.:closedeyes:

When I were a lad, we had a galvanised steel bath. Filled it from kettle and saucepans on t'gas cooker every Friday night. Youth of today don't know they've been born etc...

Link to comment
Share on other sites

4 hours ago, Tash and Bex said:

very little, we have a permanent city centre mooring now. I have been trying to work space in for a larger domestic unvented calorifier, but I just can't, unless I were to use it horizontally and even this would be a push

 

You don't have room for a 2nd/larger calorifier but do have room for an extra 200 litre plastic tank?

KISS

Thinking outside the box for a moment....

2nd/larger calorifier and go for a good cruise once a week on bath-night.

It is a boat afterall, not a flat.

Link to comment
Share on other sites

Well yes it comes down to cost, but a side effect of your novel rectangular unpressurised tank is that it will bulge and if installed eg snugly underneath a bed, break the furniture around it. I know we're talking about low pressures but still, with thinnish plastic, it will distort. Ask any balloon artist who makes more intricate pieces than simple sausage dogs, etc.

 

If you went for a much thicker tank, and/or some kind of metal framework to suppress this, then fine - but then its going to get more costly. 

 

The key aspect is the pressure - I know you've said its vented, therefore completely unpressurised, but I think if its well ventilated then there will be a horrendous inefficiency due to losses as it gets warmer. So, you want a little pressure, just a few psi would be okay. That could be achieved without a PRV, simply by having the vented outlet up a narrow tube, around roof height on the boat. Its certainly possible to do it.

 

I'd focus more on the heating source - do you already have a gas or diesel water (and/or space) heater? They're quite expensive, around £2k but it tends to be a once-off install and a piece of equipment which is very useful (in siuations where you don't, or don't want to, run the engine as in a traditional single coil calorifier). I'd spend a little more and go for bigger rather than smaller, if you've not bought one of these yet.

 

ETA - just reviewed the OP, I see you have a Webasto, that should be fine but obviously it will take some amount of time to heat up a bath-full of water.

Edited by Paul C
Link to comment
Share on other sites

Just now, smiler said:

You don't have room for a 2nd/larger calorifier but do have room for an extra 200 litre plastic tank?

KISS

Thinking outside the box for a moment....

2nd/larger calorifier and go for a good cruise once a week on bath-night.

It is a boat afterall, not a flat.

I appreciate your calling me stupid, however allow me to explain.

 

A 200L water tank can be pretty much any shape you desire, a fairly flat tank would be easily to install under the floor of the wardrobes. A domestic hot water cylinder of any description has a diameter it seems of 510mm minimum, and would be difficult to site

 

200L of water weighs well, 200kg and will certainly affect ballast, if I were to implement my plastic tank idea, the tank would be on the same side as the bath, and as only one of these vessels would be full at anytime, ballast can be allowed for. The plastic tank would not be allowed to refill until the bath was emptied thus negating the dynamic ballasting issues.

 

A DHW tank based system will cost around £600 more than the plastic tank system, not a problem if it has £600 of extra value to the system, but I am not in anyway convinced it will 

12 minutes ago, David Mack said:

 

 

Not necessarily!

A domestic vented tank could be fitted 50 feet lower than the header tank which feeds it, on which case the pressure in the tank would be a 50 ft head above atmospheric pressure.

ah yes I take your point, but if i mount my water tank 50' above the boat I would struggle with bridges!

Link to comment
Share on other sites

31 minutes ago, Tash and Bex said:

well, raised to bathwater temperature, but yes, essentially, the advantages of such a system outweigh any other choices as far as I can tell

 

 

The main advantage of this is it would make a truly first class fast breeding ground for legionella. 

 

 

Link to comment
Share on other sites

8 minutes ago, Paul C said:

Well yes it comes down to cost, but a side effect of your novel rectangular unpressurised tank is that it will bulge and if installed eg snugly underneath a bed, break the furniture around it. I know we're talking about low pressures but still, with thinnish plastic, it will distort. Ask any balloon artist who makes more intricate pieces than simple sausage dogs, etc.

 

If you went for a much thicker tank, and/or some kind of metal framework to suppress this, then fine - but then its going to get more costly. 

 

The key aspect is the pressure - I know you've said its vented, therefore completely unpressurised, but I think if its well ventilated then there will be a horrendous inefficiency due to losses as it gets warmer. So, you want a little pressure, just a few psi would be okay. That could be achieved without a PRV, simply by having the vented outlet up a narrow tube, around roof height on the boat. Its certainly possible to do it.

 

I'd focus more on the heating source - do you already have a gas or diesel water (and/or space) heater? They're quite expensive, around £2k but it tends to be a once-off install and a piece of equipment which is very useful (in siuations where you don't, or don't want to, run the engine as in a traditional single coil calorifier). I'd spend a little more and go for bigger rather than smaller, if you've not bought one of these yet.

 

ETA - just reviewed the OP, I see you have a Webasto, that should be fine but obviously it will take some amount of time to heat up a bath-full of water.

i do have a webasto, but i am thinking of adding a second, a 5KW webasto will heat 150l with a 40c rise in around 40 minutes.

 

they are commonly available from breakers yards now, as they are fitted to many diesel cars. I can get a working one for around £50!

In terms of tank expansion, I am considering a tank very similar to my waste tank, and whilst doubtless this does distort when full, it's not by much. it will be interesting to see if 40 degree water has a similar effect!

 

1 minute ago, Mike the Boilerman said:

 

 

The main advantage of this is it would make a truly first class fast breeding ground for legionella. 

 

 

indeed, I refer you to my many earlier posts on in this thread which mention that

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.