Proposed new accessible electric narrowboat.

[Willonaboat]

2 minutes ago, BoatinglifeupNorth said:

 I take it you live on your boat and think it’s all singing and dancing, how much has your big bost cost you?

 

Typo or just a personal attack?

[magnetman]

I've got quite a big pile of cut up dead hawthorn logs to get through.

 

Obviously not everyone has a derelict country estate pleasure garden in this regard but fires burning things can work. 

I would always have coal rather than diesel for a number of different reasons.

 

[Willonaboat]

2 minutes ago, magnetman said:

I've got quite a big pile of cut up dead hawthorn logs to get through.

 

Obviously not everyone has a derelict country estate pleasure garden in this regard but fires burning things can work. 

I would always have coal rather than diesel for a number of different reasons.

 

 

The problem with coal (and wood) is it's not very turn on and offable. And the dirt. And smell. And hassle of cleaning/emptying. And having to lug bags of the stuff around. Apart from all that, it's perfect.

[magnetman]

I prefer to be warm rather than cold. 

 

 

 

Disclaimer : I have a non recordable life which in no way conforms to social norms. 

 

[rusty69]

1 minute ago, magnetman said:

I prefer to be warm rather than cold. 

 

 

 

Disclaimer : I have a non recordable life which in no way conforms to social norms. 

 

Me too. With wood or coal there is very little to go wrong. To be dependant on diesel involves complexities that could render you cold and miserable. 

 

Our stove stays in pretty much all winter, and rarely leaves us cold though the black stuff is less useful than it used to be. 

 

I'm contrast we have a drip feed diesel heater that often stops working and a Chinese diesel heater that is junk. 

[Willonaboat]

 

28 minutes ago, magnetman said:

I prefer to be warm rather than cold.

 

Disclaimer : I have a non recordable life which in no way conforms to social norms. 

 

 

The problem is the smoke from your stove makes you more conspicuous than you think you are.

[BoatinglifeupNorth]

55 minutes ago, Willonaboat said:

 

Typo or just a personal attack?

No typo or personal attack?  But you seam to be going all singing and dancing with the Eco thing, so for us normal boaters with diesel and gas , I just ask how much for your(what seams) hi-tech boat has cost?

 Is it your first boat and do you think it is an investment for the future?

 

Edited December 28, 2023 by BoatinglifeupNorth

[Willonaboat]

1 hour ago, BoatinglifeupNorth said:

 I take it you live on your boat and think it’s all singing and dancing, how much has your big bost cost you?

 

36 minutes ago, BoatinglifeupNorth said:

No typo or personal attack?  But you seam to be going all singing and dancing with the Eco thing, so for us normal boaters with diesel and gas , I just ask how much for your(what seams) hi-tech boat has cost?

 Is it your first boat and do you think it is an investment for the future?

 

 

By the time it's finished it will be high spec and high tech (for a canal boat) but there's no boasting, if that's what you meant? It's a discussion about electric boats. By the time the boat is finished it will be around the £200K mark. That's self-built from a shell. If a similar spec widebeam was professionally built it would easily be north of £250K.

 

This is not my first boat. An investment for the future? It's a boat. So investment isn't a word I'd use.

[magnetman]

57 minutes ago, Willonaboat said:

 

 

The problem is the smoke from your stove makes you more conspicuous than you think you are.

Interesting way of looking at it. 

 

When I light the fire in the inner city slum ditch surrounded by endless dozens of inner city apartments I do wonder if anyone is remotely bothered by smoke from a tiny Boat chimney. 

 

On the other side of the coin (gold 22kt sov) when I light the fire on the country estate Boat I wonder if anyone can see the smoke in order for them to be remotely bothered. 

 

I know the land owner isn't. Quite the opposite in fact we understand that smoke signals help to keep away the invaders which is always good in quite a number of different ways.

 

Being conspicuous sometimes helps.

 

 

[Willonaboat]

7 minutes ago, magnetman said:

 

Being conspicuous sometimes helps.

 

 

 

Come the zombie apocolypse you'll regret those words.

 

[magnetman]

20 minutes ago, Willonaboat said:

 

Come the zombie apocalypse you'll regret those words.

 

No I won't. 

 

 

When the end of the world comes armageddon outa here. 

[BoatinglifeupNorth]

1 hour ago, Willonaboat said:

 

 

By the time it's finished it will be high spec and high tech (for a canal boat) but there's no boasting, if that's what you meant? It's a discussion about electric boats. By the time the boat is finished it will be around the £200K mark. That's self-built from a shell. If a similar spec widebeam was professionally built it would easily be north of £250K.

 

This is not my first boat. An investment for the future? It's a boat. So investment isn't a word I'd use.

 There’s a massive difference between self fit and professional Hi-Spec fit. Professional fit Hi-Spec North of 250K buys you a Narrowboat. Professional fit Hi-Spec North of £450/£500K gets you a  good widebeam.

[MtB]

3 hours ago, Willonaboat said:

a MVHR unit will be installed which are available to recover 90% of heat.

 

This claim intrigues me. I'd have thought the heat energy contained in the air being expelled is very hard to get at, especially without using refrigeration technology.

 

Using a passive heat exchanger, intuitively I'd have imagined the best that can be achieved is heating the incoming air to half way between the incoming air temp and the outgoing air temp. So if it is freezing outside and you are pumping 20c air from inside the boat to outside, and using this to warm 0c incoming air of the same volume, the best you'd achieve would be to raise it to 10c, by cooling the outgoing equal volume of air by 10c too. 

 

Do you know of any manufacturers who publish their calcs showing 90% of heat being recovered? 

 

Thanks...

 

 

 

 

 

[agg221]

30 minutes ago, MtB said:

 

This claim intrigues me. I'd have thought the heat energy contained in the air being expelled is very hard to get at, especially without using refrigeration technology.

 

Using a passive heat exchanger, intuitively I'd have imagined the best that can be achieved is heating the incoming air to half way between the incoming air temp and the outgoing air temp. So if it is freezing outside and you are pumping 20c air from inside the boat to outside, and using this to warm 0c incoming air of the same volume, the best you'd achieve would be to raise it to 10c, by cooling the outgoing equal volume of air by 10c too. 

 

Do you know of any manufacturers who publish their calcs showing 90% of heat being recovered? 

 

Thanks...

 

 

 

 

 

Your assumption is correct for a single stage, however what you actually have a is a cross-flow heat exchanger where the incoming air gets progressively warmer on the way in as it meets the outgoing air which is also progressively warmer as it gets closer to the inside (and colder as it goes outwards). Imagine breaking it down into stages.

 

Single stage:

0C in meets 20C out gives 10C

 

Three stages:

0C in meets 10C out gives 5C

5C in meets 15C out gives 10C

10C in meets 20C out gives 15C

 

Seven stages:

0C in meets 5C gives 2.5C

2.5C in meets 7.5C out gives 5C

5C in meets 10C out gives 7.5C

7.5C in meets 12.5C out gives 10C

10C in meets 15C out gives 12.5C

12.5C in meets 17.5C out gives 15C

15C in meets 20C out gives 17.5C

 

Add more stages and you get a progressively higher temperature. It takes more space and costs more due to complexity, and a bit more energy to address the back pressure, but the temperature goes up.

 

I can't help with the specifics of a published 90% efficiency as I haven't looked into this for over a decade, but the principle is sound. The main difference then seemed to be the efficiency limit of active (fan assisted) vs passive systems, for a given size. The advantage of the latter is obvious - they keep working if the battery fails - but the efficiency does (or at least did) top out at a lower percentage. They were mainly built from thin aluminium sheet which is cheap, lightweight and easy to braze up as it is pre-clad. This is the same way car heat exchangers are built.

 

Alec

Edited December 29, 2023 by agg221

[Tony Brooks]

Heat conducted depends upon the temperature difference between the two surfaces, the higher the temperature difference, the more heat is transferred. That is  a physical fact, so  splitting into stages reduces the potential heat transfer. As I said, a bit of light Googling did not support the 90% claim, and as is almost always the fact, manufacturers tests will be done under conditions likely to give favourable results, not everyday conditions. I would suspect, if you can find a reference to 90% heat transfer, that it will have an unusually high exhaust input temperature and an unusually low input fresh air temperature.

 

I am just querying the 90% claim and, again, as it is likely to run 24/7 how the electricity is provided on a narrowboat without a generator. I doubt solar will cut it, because when heat recovery is most needed, the solar output will be at its lowest.

 

I just hope that you will not be disappointed and that it will all work as claimed.

Edited December 29, 2023 by Tony Brooks

[Matt Wardman]

1 hour ago, Tony Brooks said:

Heat conducted depends upon the temperature difference between the two surfaces, the higher the temperature difference, the more heat is transferred. That is  a physical fact, so  splitting into stages reduces the potential heat transfer. As I said, a bit of light Googling did not support the 90% claim, and as is almost always the fact, manufacturers tests will be done under conditions likely to give favourable results, not everyday conditions. I would suspect, if you can find a reference to 90% heat transfer, that it will have an unusually high exhaust input temperature and an unusually low input fresh air temperature.

 

I am just querying the 90% claim and, again, as it is likely to run 24/7 how the electricity is provided on a narrowboat without a generator. I doubt solar will cut it, because when heat recovery is most needed, the solar output will be at its lowest.

 

I just hope that you will not be disappointed and that it will all work as claimed.

 

Since I started the conversation about specifics of MVHR within the thread (I think) let me add my thruppence-worth.

 

I think I have been quoting 75-80% of heat recovery from outgoing air into incoming air. My specific citation is for a Heat Recovery fan (ie a through the wall fan with a heat exchanger in the pipe); I have been using the Vent-Axia Lo Carbon Tempra units for about 8-9 years now, and they quote 'up to 78%' (link to manufacturers data). Interest points for this type of product is that they often have 12V versions available (as in the link, and I presume to allow immediate use in bathrooms), they use very little power (in this case 2W in trickle mode -> 20W on boost) ,and can be managed by thermostat or humidistat.

 

(BTW imo perhaps don't put a HR extractor fan in a shower room, since the incoming air is *always* slightly cooler than the air already in the room, so your beloved-coming-out-of-the-shower will be subjected to an airflow that feels cold, on top of the perceived cold caused by water evaporation from skin, and you may receive the appropriately vigorous customer feedback.)

I've put out a request on BuildHub to see if anyone has any info on MVHR efficiency, which I normally see quoted as "in the range 60% to 95%". How far it applies to all the ventilation air in your dwelling or boat depends on how effectively you have air sealed the unit so that all the ventilation goes through the HR system.

 

There is a decent background article on these systems, and the hows, whys and wherefores, here:

https://www.homebuilding.co.uk/advice/mvhr-the-beginners-guide

 

It's worth noting that MVHR also delivers benefits in a more controlled environment, with eg a better humidity level of perhaps 50-55% rather than fluctuations between 50% and 80% if gas cookers, or other naked flame appliances which generate water vapour as part of their process. Lower humidity can also save money since there is less water in the air to be heated up.

 

In a narrowboat setting doors are perhaps opened and closed more (but perhaps not when one is ensconced in the evening or cooler seasons), so ability to adjust temperature relatively quickly with little energy and 'thermal inertia' is a factor. 

 

Can I thank @Willonaboat for putting forward his thoughts about his own live project, which are very valuable 'feedstock' data for us to reflect on - as is real data which tends to argue either side. Much appreciated. It's all about learning and finding better ways for us to meet our own goals, whatever they are.

Edited December 29, 2023 by Matt Wardman

[Willonaboat]

10 hours ago, BoatinglifeupNorth said:

 There’s a massive difference between self fit and professional Hi-Spec fit. Professional fit Hi-Spec North of 250K buys you a Narrowboat. Professional fit Hi-Spec North of £450/£500K gets you a  good widebeam.

 

That may well be true. But the definition of a professional is someone who does something for money. It doesn't mean they do it well. Regardless, I'm not doing it for the money. I'm doing it because I'm a masochist.

[IanD]

1 hour ago, Matt Wardman said:

 

Since I started the conversation about specifics of MVHR within the thread (I think) let me add my thruppence-worth.

 

I think I have been quoting 75-80% of heat recovery from outgoing air into incoming air. My specific citation is for a Heat Recovery fan (ie a through the wall fan with a heat exchanger in the pipe); I have been using the Vent-Axia Lo Carbon Tempra units for about 8-9 years now, and they quote 'up to 78%' (link to manufacturers data). Interest points for this type of product is that they often have 12V versions available (as in the link, and I presume to allow immediate use in bathrooms), they use very little power (in this case 2W in trickle mode -> 20W on boost) ,and can be managed by thermostat or humidistat.

 

(BTW imo perhaps don't put a HR extractor fan in a shower room, since the incoming air is *always* slightly cooler than the air already in the room, so your beloved-coming-out-of-the-shower will be subjected to an airflow that feels cold, on top of the perceived cold caused by water evaporation from skin, and you may receive the appropriately vigorous customer feedback.)

I've put out a request on BuildHub to see if anyone has any info on MVHR efficiency, which I normally see quoted as "in the range 60% to 95%". How far it applies to all the ventilation air in your dwelling or boat depends on how effectively you have air sealed the unit so that all the ventilation goes through the HR system.

 

There is a decent background article on these systems, and the hows, whys and wherefores, here:

https://www.homebuilding.co.uk/advice/mvhr-the-beginners-guide

 

It's worth noting that MVHR also delivers benefits in a more controlled environment, with eg a better humidity level of perhaps 50-55% rather than fluctuations between 50% and 80% if gas cookers, or other naked flame appliances which generate water vapour as part of their process. Lower humidity can also save money since there is less water in the air to be heated up.

 

In a narrowboat setting doors are perhaps opened and closed more (but perhaps not when one is ensconced in the evening or cooler seasons), so ability to adjust temperature relatively quickly with little energy and 'thermal inertia' is a factor. 

 

Can I thank @Willonaboat for putting forward his thoughts about his own live project, which are very valuable 'feedstock' data for us to reflect on - as is real data which tends to argue either side. Much appreciated. It's all about learning and finding better ways for us to meet our own goals, whatever they are.

The humidity control you mention is a bonus with MHVR -- but of course on a gas-free boat you don't have anything like as much generation of water vapour. It's very noticeable on a conventional boat that if you get up on a cold morning and go to make the tea (kettle on gas hob) the windows in the galley go from clear to covered in condensation by the time the kettle has boiled -- and that this doesn't happen on a hybrid boat (electric or induction hob kettle).

 

It'll be interesting to see how the numbers come out for your entire plan once you put realistic ones in, to see how much actual benefit (e.g. lower required heating load) each idea gives you. My feeling -- based on some handwaving engineering guesstimates -- is that the benefits will be much smaller than a house because you can't realistically get anywhere near the huge insulation thickness needed to get the the point where the other much smaller heat losses make a significant difference.

 

If you could build a boat to Passivhaus standards then things would be very different and it might even be possible to get to an all-solar boat even in winter, but the space restrictions mean this is not possible on a narrowboat -- it may be on a wideboat with much more width (and more height) available, but that's not what you're trying to do.

[Willonaboat]

10 hours ago, MtB said:

 

This claim intrigues me. I'd have thought the heat energy contained in the air being expelled is very hard to get at, especially without using refrigeration technology.

 

Using a passive heat exchanger, intuitively I'd have imagined the best that can be achieved is heating the incoming air to half way between the incoming air temp and the outgoing air temp. So if it is freezing outside and you are pumping 20c air from inside the boat to outside, and using this to warm 0c incoming air of the same volume, the best you'd achieve would be to raise it to 10c, by cooling the outgoing equal volume of air by 10c too. 

 

Do you know of any manufacturers who publish their calcs showing 90% of heat being recovered? 

 

Thanks...

 

 

 

Several. But by way of one example because I'm just your personal Mr Feckin' Google [joke!] see here: https://www.blauberg.co.uk/en/horizontal-residential-heat-recovery-unit

 

Click on Downloads for the link to the data sheet.

 

Maximum efficiency of this unit is 94%.

 

 

Edited December 29, 2023 by Willonaboat

[MtB]

17 minutes ago, Willonaboat said:

 

Several. But by way of one example because I'm just your personal Mr Feckin' Google [joke!] see here: https://www.blauberg.co.uk/en/horizontal-residential-heat-recovery-unit

 

Click on Downloads for the link to the data sheet.

 

 

Thanks, but I can see any efficiency calculations on that data sheet. Just unsupported assertions of up to 94% efficiency. Is this the data sheet you meant? 

https://www.blauberg.co.uk/en/amfile/file/download/file/3023/product/6167/

 

My gut feeing is this is a semantics problem, as so often is the case. I think a 100% efficient heat exchanger will recover 50% of the available heat in the outgoing air, for the reasons I stated earlier. Nowhere in the link can I see a claim that 94% heat in the outgoing air is recovered.

 

Just an un-defined 'efficiency' figure of 94%, which isn't the same thing at all as "a MVHR unit will be installed which are available to recover 90% of heat."

 

I think it is dishonest marketing as the writing is always arranged to lead the reader to the assume they mean what you wrote, when they didn't actually say that. 

 

 

Edited December 29, 2023 by MtB
Missing word

[agg221]

2 hours ago, Tony Brooks said:

Heat conducted depends upon the temperature difference between the two surfaces, the higher the temperature difference, the more heat is transferred. That is  a physical fact, so  splitting into stages reduces the potential heat transfer.

This is true, but it affects rate of heat transfer, rather than absolute temperature differential (if you put a hot object and a cold object either side of a sheet of material in a sealed, highly insulated box the rate of heat transfer across the sheet will start off higher and gradually fall as they get closer in temperature, but will eventually equalise).

 

You can address this practically by having larger heat transfer surfaces, thinner walls, higher conductivity materials and longer residence time. Thin aluminium sheet deals with two of these and a larger unit deals with a third. Longer residence time is reasonably achievable when you only need small numbers of air changes in a relatively small volume such as a boat interior.

 

There are some very exotic solutions based on laminar flow channels that can achieve extremely high efficiency heat transfer - known as printed shim or compact heat exchangers. If you look these up today you will find that the thermal transfer rates are fantastic in an extremely small volume. However, you will also notice that they are made in high temperature materials with very high service temperature and pressure ratings quoted. This is for several reasons, most notably that the manufacturing process does not work for aluminium. This has now been addressed (https://uspto.report/patent/app/20210220943) so this is an emerging technology to look out for over the next five years or so.

 

More broadly than your original point Tony, but with reference to other posts above, I mention this not because I think anyone currently building a boat should be hanging on and waiting for this technology to become commercially available but because it addresses the point that technologies originated in one industry sector can often 'unblock' the development of another technology in a different sector. There are a number of posts in this thread along the lines of 'it will never work' but living in a world of commercial research and development, I rather disagree with that mindset and would point out that if everyone took the view that because something has not been done it cannot be done then we would never develop anything new.

 

Alec

[IanD]

34 minutes ago, Willonaboat said:

 

Several. But by way of one example because I'm just your personal Mr Feckin' Google [joke!] see here: https://www.blauberg.co.uk/en/horizontal-residential-heat-recovery-unit

 

Click on Downloads for the link to the data sheet.

 

Maximum efficiency of this unit is 94%.

 

 

Looks good at first glance, but as usual the devil is in the details. The *minimum* airflow rate is something like 10l/s (maximum is 38l/s) which is *way* too high for a boat, especially a narrowboat.

 

The implication is that the intended use is for large kitchen/bathroom/wetroom extractor fans, to stop them sucking lots of heat from the inside to the outside when there's a *lot* of air being moved -- which is absolutely a good thing for that application, but not for background air exchange in a small living space like a narrowboat.

 

12 minutes ago, agg221 said:

[snip]

 

More broadly than your original point Tony, but with reference to other posts above, I mention this not because I think anyone currently building a boat should be hanging on and waiting for this technology to become commercially available but because it addresses the point that technologies originated in one industry sector can often 'unblock' the development of another technology in a different sector. There are a number of posts in this thread along the lines of 'it will never work' but living in a world of commercial research and development, I rather disagree with that mindset and would point out that if everyone took the view that because something has not been done it cannot be done then we would never develop anything new.

 

Alec

 

Nobody is saying "it will never work", just that the benefit in a narrowboat is likely to be very small because the amount of air being moved is also very small (see above post), and boat insulation is way worse than a Passivhaus -- where units like this are typically used because other heat losses have been drastically reduced so loss via ventilation is a large part of what remains.

 

It's like saying that because they used to super-smooth/polish the skin/rivets of Spitfire reconnaisance planes to reduce drag and get that bit of extra speed, this is a good reason to do the same on your Volvo. It's not, because the situations are very different.

 

I'm all for using new technology when it delivers a significant benefit, otherwise my boat wouldn't be like it is. But it's important to crunch the numbers to see whether something that delivers such a benefit in a very different application also does so in a narrowboat, not just assume that it will because it works somewhere else.

Edited December 29, 2023 by IanD

[Willonaboat]

5 minutes ago, IanD said:

 

Looks good at first glance, but as usual the devil is in the details. The *minimum* airflow rate is something like 10l/s (maximum is 38l/s) which is *way* too high for a boat, especially a narrowboat.

 

The implication is that the intended use is for large kitchen/bathroom/wetroom extractor fans, to stop them sucking lots of heat from the inside to the outside when there's a *lot* of air being moved -- which is absolutely a good thing for that application, but not for background air exchange in a small living space like a narrowboat.

 

I've been looking at models suitable for my widebeam. Other MVHR units are available with lower airflow rates but someone with an interest in narrowboats would need to do that research.

[IanD]

Just now, Willonaboat said:

 

I've been looking at models suitable for my widebeam. Other MVHR units are available with lower airflow rates but someone with an interest in narrowboats would need to do that research.

Absolutely -- and needs to look at what the actual heat savings would be in a narrowboat (or wideboat) with much lower airflow rates and poorer insulation than a house. Numbers matter... 😉

[magnetman]

Also someone looking to have an accessible electric Boat based in London may not ever get to narrow canals in the first place. 

 

I would be looking at something a bit wider myself. Not a big fat horror box but something like 9ft beam. It may seem a pointless width for a Boat but it gives more space than a narrow and one does not receive endless streams of abuse from Harold Shipman beard,-wearing owners of narrow Boats.