Cylinder Jacket

[Ray]

Has anyone fitted a cylinder jacket to their calorifier?

 

Better still, has anyone fitted a cylinder jacket to a 55 litre Surecal vertical calorifier?

 

We can't find a suitable jacket anywhere - cylinder is approx 80cm high and 35cm in diameter and we're bit tight for space to get the jacket in.

[Phil Ambrose]

Has anyone fitted a cylinder jacket to their calorifier?

 

Better still, has anyone fitted a cylinder jacket to a 55 litre Surecal vertical calorifier?

 

We can't find a suitable jacket anywhere - cylinder is approx 80cm high and 35cm in diameter and we're bit tight for space to get the jacket in.

 

I have a Surecal same size but mounted horizontaly, however mine came fitted with foam jacket in a nice shade of blue and came with a warranty claiming temp loss of no more than deg 1c per hour. Is your calorifier just plain copper or is it like mine with a hard foam jacket?

[alan_fincher]

I think all Suejust / Surecal cylinders probably come cased in the blue covered foam, don't they ?

 

Personally I am dubious that just putting a cylinder jacket on it will cause significantly more heat to be retained.

 

Mine doesn't feel very warm on the outside even when piping hot inside, so I don't think more insulation would achieve a lot.

[Ray]

We've got the foam but have an engine that only heats the water to around 70 degrees.

 

At 1 degree per hour loss, the water is barely warm enough for a shower the following morning and definitely not warm enough if SWMBO does the washing up after the evening meal the previous day. My guess is that the loss we're experiencing is a bit neare 2 dgrees per hour if we use any water after we've moored up.

[bottle]

Using water from a calorifier will reduce its temperature a lot quicker than the heat lost through the insulation.

 

Solution . Have shower at night, wash up after the shower or the next day.

 

A little more serious.

 

You may have a heat loss via the pipework, backward convection to the engine.

[Ray]

Keith

 

We've been through everything with Surecal and Beta and have come to the conclusion that because the engine's thermostat is opening at around 70 degrees we're not heating the water enough when cruising to overcome heat loss overnight. Unfortunately Beta haven't recommended replacing the thermostat with anything that opens at a higher temperature. I presume that if we changed it ourselves we'd invalidate the warranty.

 

We've got an NRV in the pipework to stop back convection. I wonder if we could reduce the pressure on the supply to the calorifier in the hope that the water would (relatively) trickle in at the bottom, rather than enter with force.

 

We do have a reasonable length run between calorifier and bathroom (about 10ft) and kitchen (about 18ft), but I suspect this is no worse than other people's.

 

We can keep the water hot enough if we don't draw anything the night before (so we tend to shower midday) but even drawing anything more than a couple of litres causes the water temperature to drop like a stone overnight.

 

The insulation jacket idea came from a friend who has fitted one on his domestic cylinder at home and says it makes quite a difference to his heating bills.

[nb Innisfree]

A cyl jacket on top of foam insulation will make little difference. Whats the capacity of your calorifier?, we have a dedicated 12 gal calorifier for our bathroom and get 2 good showers 15 hrs after heating (80deg engine) with no hot usage until then. We need to run engine for 2 hours to achieve this. I would guess you are asking too much of your calorifier by having engine at 70 deg and waiting - 18 hrs? - for a shower.

 

Edited to add our pipe run from cal to shower is about 3' max

Edited August 17, 2009 by nb Innisfree

[Ray]

18 Hours! We're hardly ever stationary for half that long! (Well, maybe we are, but only for a little bit longer than half).

 

It is the 70 degrees that causes the problem and the jacket was just a suggestion to try and overcome it. As indicated above, I'd be happy to change the thermostat to raise the base temperature but Beta would probably say that this would invalidate the warranty so our only option is to look at something that stops the drastic fall in temperature.

 

What does puzzle me is that the temperature drop is so noticeable for such a small increase in the water drawn off from the cylinder the night before. 2 - 4 litres seems to have virtually no impact, double that and the water's no more than luke warm the following morning.

[colin stone]

It is the 70 degrees that causes the problem and the jacket was just a suggestion to try and overcome it. As indicated above, I'd be happy to change the thermostat to raise the base temperature but Beta would probably say that this would invalidate the warranty so our only option is to look at something that stops the drastic fall in temperature.

 

I'm assuming the engine is a modern engine and if so I'm amazed that the thermostat is opening at 70C. I would have thought at least 10c higher. I know many of the Beta engines are Kubotas at heart and the thermostat on my Kubota generator engine starts to open at 83C.

[RLWP]

Just a thought. How is your calorifier installed? Are you taking the hot water out of the top and putting the cold in at the bottom? Is there any way you are mixing cold water coming in to the calorifier with the hot water that is being taken out?

 

Richard

[dor]

Change the thermostat and keep the old one until your warranty expires. Swap back if you need to get Beta to look at the engine for any reason.

[Ray]

Was tempted to change the thermostat (and may still do that).

 

Cold water goes in at the bottom and hot out at the top, we've even isolated the cold feed to the mixer to make sure that wasn't causing a problem.

 

We've measured the temperature of the coolant in the engine after we've stopped cruising and it was just over 70 degrees. We told Beta and they said that the stat opens slightly around 70 degerees and is fully open at 80 degrees. They think it is because we don't work the engine hard. Unfortunately I'm not technically minded so I can't argue that point (if I need to).

 

A colleague says that Beta's story is bullsh*t as the stat is either open or closed (and the Beta manual certainly implies a running temperature of around 85 degrees.

 

Does anyone else run a Beta 43 and have a Surecall 55 litre calorifier? If so, how is your hot water in the morning?

[nb Innisfree]

18 Hours! We're hardly ever stationary for half that long! (Well, maybe we are, but only for a little bit longer than half).

 

It is the 70 degrees that causes the problem and the jacket was just a suggestion to try and overcome it. As indicated above, I'd be happy to change the thermostat to raise the base temperature but Beta would probably say that this would invalidate the warranty so our only option is to look at something that stops the drastic fall in temperature.

 

What does puzzle me is that the temperature drop is so noticeable for such a small increase in the water drawn off from the cylinder the night before. 2 - 4 litres seems to have virtually no impact, double that and the water's no more than luke warm the following morning.

 

You say you shower midday and assuming you stop charging early evening then that would be very nearly 18 hrs, too long a priod in your set up IMO

[paulcatchpole]

We've got the foam but have an engine that only heats the water to around 70 degrees.

 

At 1 degree per hour loss, the water is barely warm enough for a shower the following morning and definitely not warm enough if SWMBO does the washing up after the evening meal the previous day. My guess is that the loss we're experiencing is a bit neare 2 dgrees per hour if we use any water after we've moored up.

 

Our unknown-make (large) Calorifer is c. 110L, old enough to have imperial pipe fittings, and came sprayed in PU foam.

 

 

With an air-cooled engine, we heat water in it with a house gas boiler to 70deg C, and once hot, it's hot enough for washing up over 30 hrs later.

 

Are you sure you're not transferring the heat back to produce a lovely warm engine in the mornings?

 

PC

[Ray]

To clarify a few facts.

 

We have an NRV between engine and calorifier so don't believe the water is going backwards overnight - especially because, if we don't draw any water off between mooring up and breakfast, there's plenty of it and it is warm enough in the morning.

 

We don't leave it 18 hours! We usually cruise until 6 or 7pm, stop for the night, eat on board, wash up to keep the place tidy, and then (eventually) go to bed. We're usually up by 7am and the water is only cool when we wash before breakfast. We do shower during the day and moor up after cruising for a few hours to do so and then we carry on cruising afterwards so that we reheat the water.

 

Interestingly, we have a twin coil calorifier, using the lower coil for the engine and the top coil to heat the cylinder from our Alde boiler. We've aded a cylinder thermostat and the Alde fires up based on that thermostat's state - it is set to trip at about 62 degrees.

 

Even if we don't draw any water once the Alde has stopped heating, it is only a couple of hours before the Alde cuts back in again because the cylinder thermostat has called for more heat.

 

And we can't be getting convection through the top coil because the Alde is connected to the cylinder via an electronic gate valve which only opens when the Alde is heating the water.

 

I've spoken to the person who installed our engine when the boat was new. He says that he has the same problem with keeping his water hot overnight although I don't know what make of calorifier he has.

[nb Innisfree]

To clarify a few facts.

 

We have an NRV between engine and calorifier so don't believe the water is going backwards overnight - especially because, if we don't draw any water off between mooring up and breakfast, there's plenty of it and it is warm enough in the morning.

 

We don't leave it 18 hours! We usually cruise until 6 or 7pm, stop for the night, eat on board, wash up to keep the place tidy, and then (eventually) go to bed. We're usually up by 7am and the water is only cool when we wash before breakfast. We do shower during the day and moor up after cruising for a few hours to do so and then we carry on cruising afterwards so that we reheat the water.

 

Interestingly, we have a twin coil calorifier, using the lower coil for the engine and the top coil to heat the cylinder from our Alde boiler. We've aded a cylinder thermostat and the Alde fires up based on that thermostat's state - it is set to trip at about 62 degrees.

 

Even if we don't draw any water once the Alde has stopped heating, it is only a couple of hours before the Alde cuts back in again because the cylinder thermostat has called for more heat.

 

And we can't be getting convection through the top coil because the Alde is connected to the cylinder via an electronic gate valve which only opens when the Alde is heating the water.

 

I've spoken to the person who installed our engine when the boat was new. He says that he has the same problem with keeping his water hot overnight although I don't know what make of calorifier he has.

 

Is there a radiator anywhere in the circuit? if so could it be back circulating to that? Sometimes it's said that the flow and return pipes should carry on and connect together after cals and rads which is wrong, if you have this setup then it could be circulating that way and losing heat through the piping.

[Ray]

Thanks for the suggestion.

 

Our radiators are blocked off by another electronically driven gate valve which is only open when the room stat asks for heat and we seldom use that as the dual fuel stove keeps the boat warm enough.

 

To the best of my knowledge the heat is either disappearing through the insulation or the pressure of the cold water entering the cylinder is forcing it to mix with the hot water and adversely cool it down, if that is possible. Having said that, we only have a bog standard Sureflow water pump, the same as most other people, so I can't see that that is the reason.

 

If the heat is escaping through the foam, then we think a cylinder jacket might reduce that.

[nb Innisfree]

Thanks for the suggestion.

 

Our radiators are blocked off by another electronically driven gate valve which is only open when the room stat asks for heat and we seldom use that as the dual fuel stove keeps the boat warm enough.

 

To the best of my knowledge the heat is either disappearing through the insulation or the pressure of the cold water entering the cylinder is forcing it to mix with the hot water and adversely cool it down, if that is possible. Having said that, we only have a bog standard Sureflow water pump, the same as most other people, so I can't see that that is the reason.

 

If the heat is escaping through the foam, then we think a cylinder jacket might reduce that.

 

Ref my previous post, what happens to the flow and return pipes after they have reached the furthest rad/cal, do they carry on and join together?

 

Heat can't escape through foam, it is polyurethane foam which has a very high insulation value, adding a jacket will have a miniscule effect

Edited August 17, 2009 by nb Innisfree

[Ray]

The pipework to the lower coil on the calorifier is a loop from the engine and back to the engine, with an NRV on the input to the calorifier.

 

The upper coil is connected to the Alde (which we don't normally use when cruising). There is a T junction within a couple of feet of the boiler. Each leg goes to the above mentioned gate valves, then to the calorifier or the radiator circuit. The returns from both combine at another T junction just a few feet from the boiler and go back to the boiler.

 

The calorifier manufacturer suggest that the engine isn't getting hot enough during the day to heat the water enough to overcome the natural loss of temperature overnight. As I previously indicated, the water remains hot enough if we don't use it, but the minute we draw off more than a washing up bowl full, the water is only tepid the following mroning.

 

Who's nicked me hot water?

[Machpoint005]

I can't swear to the manufacturer of our calorifier, without looking at it, but we're heating it with a Beta 43 engine. That has foam insulation, and we get lots of loverly hot water (too hot to touch, just after we stop). If I remember to close the stopcock between the engine and the calorifier inlet, it's hot enough to wash up the next morning (not a greasy frying pan, though!). If we use no hot water overnight, it's still pretty hot the next morning.

 

I don't think your engine is getting up to temperature. Regardless of the thermostat setting, have you got an enormous skin tank keeping the whole thing cool? I agree that your hot water tank is giving you a nice warm engine in the morning, though - all that heat must be going somewhere!

[nb Innisfree]

The pipework to the lower coil on the calorifier is a loop from the engine and back to the engine, with an NRV on the input to the calorifier.

 

The upper coil is connected to the Alde (which we don't normally use when cruising). There is a T junction within a couple of feet of the boiler. Each leg goes to the above mentioned gate valves, then to the calorifier or the radiator circuit. The returns from both combine at another T junction just a few feet from the boiler and go back to the boiler.

 

The calorifier manufacturer suggest that the engine isn't getting hot enough during the day to heat the water enough to overcome the natural loss of temperature overnight. As I previously indicated, the water remains hot enough if we don't use it, but the minute we draw off more than a washing up bowl full, the water is only tepid the following mroning.

 

Who's nicked me hot water?

 

It's difficult to picture your circuit from a description, can you trace the circuit from the upper coil and check whether it can make a return circuit anywhere as I am sure heat

must be escaping in this way

 

It may be the DHW is circulating somewhere, what size pipes exit the top of cal? too large a bore could cause thermo syphon circulation within the pipe which would then radiate away

 

When we heat our cal with our Mikuni, flow temp doesn't exceed 65 deg, cuts out at 70deg, and we have plenty of hot water so I don't think your engine temp at 70 deg is an issue.

[Ray]

Thanks for the continuing suggestions.

 

We have plenty of hot water when we stop. We have plenty of hot water when the boiler's fired up. What we don't have is the same quantity/quality of hot water if we use more than a trickle or, in the case of the boiler, if we don't use any and just leave it for a while.

 

We've taken temperature readings night and morning and can confirm that the engine is no warmer in the morning than anything else that is metal in the same area that isn't in direct contact with the canal.

 

We've used 15mm plastic pipe for all the plumbing except for the hot water feed to the taps, and that is via a 15mm connection on top of the calorifier. The water pump doesn't run other than when taps are running, so there's no water movement except when we intend there to be.

 

We fitted the boat out ourselves so are happy that the only circuits are the three individual loops. One is blocked by the NRV and the other two by the electronic controlled gate valves (and before we fitted them, hand worked gate valves, which didn't give any different results).

 

Initially we only used the engine to heat the calorifier via the bottom coil, the top coil was completely unused/unconnected to anything, and we still had the problem.

 

We've even changed the NRV to no effect.

 

The most puzzling thing is that it only requires a relatively small amount of water to be drawn off to make the difference between having hot water in the morning and having tepid water in the morning.

[nb Innisfree]

What do you call a relatively small amount of water? when hot water arrives at your kitchen tap through 18' of piping it's already drawn over a gallon of cold water into the cal + the amount you actually use, and that is with 15mm pipe, it's 3.5 gal+ with 22mm so that adds up to quite a bit of dilution

[Ray]

We did some experiments with measured amounts of water, 1 litre, 2 litres and 4 litres (at the tap). We just took the first amount from the tap, didn't wait for it to get hot. Anything above about 4 litres had the detrimental effect described.

 

Sounds like we'd better put 15mm back where we have the 22mm pipe if that is going to help.

[alan_fincher]

Regardless of the thermostat setting, have you got an enormous skin tank keeping the whole thing cool?

If you have the largest skin tank ever built, but your thermostat is working, doing what it was intended to do, the engine should still reach thermostat temperature.

 

No water should go to the skin tank until the stat opens, and if the skin tank is particularly efficient, it just means the stat will close again sooner.

 

You can't have a too big skin tank, (other than the expansion of a very large volume of water can sometines cause problems, if the engine expansion space can't handle it).