Heating water

[DHutch]

So having hot water going around the coils will not harm an empty calorifier?

No, it should be fine.

- The issue was raised on here before, but yeah, it will be fine.

- The water/tank can only get to around 100c, which i will do anyway.

 

 

Daniel

[blackrose]

I've been looking into thermostatic mixing valves and on several models the fitting instructions say that they must be installed no more than 2 metres from the outlet. I can't think why this would be but it kind of scuppers my idea about fitting a single TMV to my calorifier.

 

http://content.honeywell.com/uk/homes/Cata....6%20TMV200.pdf

[chris w]

I've been looking into thermostatic mixing valves and on several models the fitting instructions say that they must be installed no more than 2 metres from the outlet. I can't think why this would be but it kind of scuppers my idea about fitting a single TMV to my calorifier.

 

http://content.honeywell.com/uk/homes/Cata....6%20TMV200.pdf

 

In the pdf to which you refer Mike, they say it is "for health reasons". I can only presume that having warm water rather than very hot water in the pipes may lead to bacterial growth. Presumably if the water were very hot there would be no bacteria and hence even when the hot water cooled there would still be no bacteria.

 

However, this is only a guess as I'm no microbiologist (yet! )

 

Chris

[ChrisPy]

In the pdf to which you refer Mike, they say it is "for health reasons". I can only presume that having warm water rather than very hot water in the pipes may lead to bacterial growth. Presumably if the water were very hot there would be no bacteria and hence even when the hot water cooled there would still be no bacteria.

 

However, this is only a guess as I'm no microbiologist (yet! )

 

Chris

the water in your hot pipes will be cold 15 minutes after you've taken your shower anyway, so that doesn't seem to be logical.

[blackrose]

the water in your hot pipes will be cold 15 minutes after you've taken your shower anyway, so that doesn't seem to be logical.

 

I think I'll ring a plumbers merchants and ask them before I spend my fifty quid on a TMV and start hacking into my plumbing.

 

Someone from another boat just told me I should be addressing the problem at the source - i.e. fitting a thermostatic valve to the hot water feed from the engine to the calorifier coil. This would simply reduce the flow to the coil above the set temperature. It seems like a much simpler idea and it sounds a lot cheaper too - 6 quid instead of £50!

[chris w]

I think I'll ring a plumbers merchants and ask them before I spend my fifty quid on a TMV and start hacking into my plumbing.

 

Someone from another boat just told me I should be addressing the problem at the source - i.e. fitting a thermostatic valve to the hot water feed from the engine to the calorifier coil. This would simply reduce the flow to the coil above the set temperature. It seems like a much simpler idea and it sounds a lot cheaper too - 6 quid instead of £50!

 

Mike

 

try Ebay. I got a brand new boxed well-known name TMV for £12 (no-one else bid). It works perfectly and is adjustable from 30-50 degC.

 

A TMV BTW doesn't "reduce the flow". It mixes the correct amount of cold water with the hot to get the set output temperature.

 

Chris

Edited September 6, 2007 by chris w

[blackrose]

A TMV BTW doesn't "reduce the flow". It mixes the correct amount of cold water with the hot to get the set output temperature.

 

Chris

 

Thanks chris,

 

I was talking about an ordinary thermostatic valve (like the ones on your radiators) which would close down and restrict flow from the engine feed to the coil in the calorifier when it reached a specified temperature, rather than a thermostatic mixing valve. It only needs plumbing into one pipe & just seems like a much simpler solution. It also addresses the problem at source rather than compensating for the water in the calorifier being too hot in the first place.

 

TMVs are used in domestic hot water applications (hospitals, schools, etc) because people still need water from their taps so hot & cold water is mixed rather than restricted, but calorifier coils don't need hot water from the engine once once the whole thing is piping hot, and as a heat sink for the engine the calorifier serves no purpose once it's hot either.

Edited September 6, 2007 by blackrose

[smileypete]

Thanks chris,

 

I was talking about an ordinary thermostatic valve (like the ones on your radiators) which would close down and restrict flow from the engine feed to the coil in the calorifier when it reached a specified temperature, rather than a thermostatic mixing valve. It only needs plumbing into one pipe & just seems like a much simpler solution. It also addresses the problem at source rather than compensating for the water in the calorifier being too hot in the first place.

 

Hi Blackrose,

 

I think the problem with rad thermostats is they work off air temperature, and quite a low one at that.

 

The main risk (though next to non existent!) from bacteria is breathing them in ie while bathing, thermostatic shower mixers aren't that expensive and well worth having, so I'd just use one of them for the shower.

 

For sinks and basins ideally I'd just put a TMV at the nearest convenient point to feed them all, ideally near to the most used tap.

 

As Chris says TMVs can be had quite cheaply from Ebay.

 

 

As an aside, one way to get a washing machine to do a warm wash without using it's heater may be to feed the inlet via a cheap thermostatic shower mixer.

 

Then all that needs to be done is turn the control to hot while it fills for the main wash.

 

All IMHO etc...

 

cheers,

Pete.

Edited September 6, 2007 by smileypete

[blackrose]

Hi Blackrose,

 

I think the problem with rad thermostats is they work off air temperature, and quite a low one at that.

Thanks, perhaps I was wrong when I mentioned rad valves, but isn't there such a thing as a thermostatic valve that works off water temp?

[smileypete]

Thanks, perhaps I was wrong when I mentioned rad valves, but isn't there such a thing as a thermostatic valve that works off water temp?

 

It'd be much better to heat the calorifier to engine temp then regulate the temperature of taps and showers.

 

This gives more usable hot water from the cylinder, and the cylinder will stay hot enough for longer.

 

cheers,

Pete.

[chris w]

Yes that's a much better idea. It's like having "concentrated" hot water which you then "dilute to taste". It'll go so much further.

 

Chris

[Dave Hannigan]

In the pdf to which you refer Mike, they say it is "for health reasons". I can only presume that having warm water rather than very hot water in the pipes may lead to bacterial growth. Presumably if the water were very hot there would be no bacteria and hence even when the hot water cooled there would still be no bacteria.

 

However, this is only a guess as I'm no microbiologist (yet! cool.gif )

 

 

You are right, Chris,the specific one being legionella.There are a whole host of regs governing water temp and delivery times.

 

Dave

[blackrose]

Yes that's a much better idea. It's like having "concentrated" hot water which you then "dilute to taste". It'll go so much further.Chris

Fair enough, a TMV it is then.

You are right, Chris,the specific one being legionella.There are a whole host of regs governing water temp and delivery times.Dave

The regs are there for domestic installation particularly as TMVs are commonly installed in hospital & school hot water systems. However, as far as I can see the water temp in most calorifiers fluctuates wildly depending on what the boat has been doing. Mine varies from tepid to scalding hot so in my opinion there's no need to fit a TMV to each outlet or within 2 metres of the sinks or shower because sometimes what's in the calorifier is only going to be warmish and therefore potentially full of bacteria anyway. So for what we're trying to achieve, one TMV fitted on the hot water pipe from the calorifier should be quite sufficient. Edited September 7, 2007 by blackrose

[ChrisPy]

You are right, Chris,the specific one being legionella.There are a whole host of regs governing water temp and delivery times.

 

Dave

we all know that when we turn the hot tap on at home the water runs cold, then warm, then hot.

 

what are these regulations? do they apply to domestic installations? if not then how and why are they relevant to boats?

[Dave Hannigan]

we all know that when we turn the hot tap on at home the water runs cold, then warm, then hot.

 

what are these regulations? do they apply to domestic installations? if not then how and why are they relevant to boats?

 

Chris I wasn't offering a judgement on the validity of the regs for domestic or boat use, I was merely answering the question posed earlier as to why the TMV instructions stated a max of 2m pipework from the valve.

 

Dave

[chris w]

we all know that when we turn the hot tap on at home the water runs cold, then warm, then hot.

 

what are these regulations? do they apply to domestic installations? if not then how and why are they relevant to boats?

 

 

Water stored at 60degC or above will not support legionella bacteria. So, even when that water cools in the pipes, it still does not contain the bacteria. However, if water is introduced into the calorifier which happens to contain legionella bacteria and that water is stored at below 60degC (say 40's degC, viz: hand hot) then legionella bacteria will multiply and when the water cools in the pipes, those pipes WILL still contain the bacteria.

 

Chris

[ChrisPy]

Water stored at 60degC or above will not support legionella bacteria. So, even when that water cools in the pipes, it still does not contain the bacteria. However, if water is introduced into the calorifier which happens to contain legionella bacteria and that water is stored at below 60degC (say 40's degC, viz: hand hot) then legionella bacteria will multiply and when the water cools in the pipes, those pipes WILL still contain the bacteria.

 

Chris

that makes sense.

same rules as warming up food in a way, I guess all bacteria are much the same..

[Amicus]

Thanks, perhaps I was wrong when I mentioned rad valves, but isn't there such a thing as a thermostatic valve that works off water temp?

Yus, dat'll be a 'cylinder stat'

As yoused on a domestic hot water cylinder.

You could also use a rad-stat with a remote sensor

Edited September 8, 2007 by Amicus

[blackrose]

Water stored at 60degC or above will not support legionella bacteria. So, even when that water cools in the pipes, it still does not contain the bacteria. However, if water is introduced into the calorifier which happens to contain legionella bacteria and that water is stored at below 60degC (say 40's degC, viz: hand hot) then legionella bacteria will multiply and when the water cools in the pipes, those pipes WILL still contain the bacteria.

 

Chris

 

Yes the pipes will contain that legionella, but as you say, it has to be there in the first place.

 

However, when I'm on my mooring on shore power my immersion heater isn't on 24 hours a day so cold water is fed into the calorifier and without leaving it on constantly (which I find wasteful), I can't guarantee that the water will be hot enough to kill potential pathogens. Similarly, when I'm out cruising like yesterday, the engine may not be run for the the next couple of days. Right now I'm moored up in Teddington (just seen Ian on his beautiful replica Dutch barge Elessina), so as I use the hot water the calorifier will be replenished with cold water from the tank, thus lowering the temperature to that at which harmful bacteria can grow.

 

All I'm saying is that in this situation it's pointless having a TMV within 2m of each outlet in an attempt to maintain the water temperature above 60deg C in the pipes.

[ChrisPy]

....... it's pointless having a TMV within 2m of each outlet in an attempt to maintain the water temperature above 60deg C in the pipes.

good point, unless we are on a shore line with an immersion heater, the calorifier will often be cold or only slightly warm

[Amicus]

Yus, dat'll be a 'cylinder stat'

As yoused on a domestic hot water cylinder.

You could also use a rad-stat with a remote sensor

 

Further to my above, I did a bit of a shuffle up that there Cyber SuperHighway chat-harry and stumbled across,

 

Cyltrol

http://www.invensyscontrolseurope.com/Inve...rCyltrolMk3.htm

 

Rad-stat mit remote sensor

http://www.invensyscontrolseurope.com/Inve...DERCONTROLS.htm

Edited September 10, 2007 by Amicus