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Domestic heat and water with three inputs


ramblin

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In farm houses I know, with several heat sources; range/stove/oil and various outputs, they just have a small mixing tank, for get its formal name if I ever knew it, but about a foot in dia and 6inch in height, with tank fittings in a circle round top and bottom of the side. All heat sources leave the bottom and return to the top, all rad loops leave the top and return at the bottom. No valves, just switch the pumps with thermostates/timers.

 

 

Daniel

 

You're thinking of a Dunsley Neutraliser http://www.dunsleyhe...eutralizer.html. Not a thermal heatstore, but simply a neutral point for the feed and return legs of a system with more than one heatsource, allowing a mix of different pumped systems.

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You're thinking of a Dunsley Neutraliser http://www.dunsleyhe...eutralizer.html. Not a thermal heatstore, but simply a neutral point for the feed and return legs of a system with more than one heatsource, allowing a mix of different pumped systems.

 

Yes, that is exactly what it is, a type-c, tried to find it over lunch, but no such luck. Simple, effective.

 

Daniel

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Yes, that is exactly what it is, a type-c, tried to find it over lunch, but no such luck. Simple, effective.

 

Daniel

 

Checked the link, has anyone used these in narrowboats? It looks simple enough but wondering about pros/cons compared to using valves.

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Thanks all for advise. I think pinning down this system is important before spending too much time on masterplans and cost/time/pleasure/pain estimates!

 

Following comments ive revised plan to simplify the engine cooling circuit. This doesnt allow the engine to directly heat rads which is probably a very good thing having given more consideration to the needs of the engine! Also the burner / diesel loop has been changed to vented system but still have the motorised valve for water / radiator selection. I also left the heat exchanger for the radiator circuit as it doesnt seem correct to rely on the diesel heater/MF pump to circulate around the radiator loop.

 

Ive still loads of questions so any help would be awesome!

 

Engine

---------

Is a series calorifier-skin tank connection from an engine with only one cooling outlet wise (will ensure the primary coil, skin tank and connecting pipework are generously sized to minimise losses)?

 

Should engine loop comprise stainless and rubber components only (not sure what material the engine cooling components are made of - presume alloy)?

 

Header Tank

----------------

Is it realistic to get enough static head on the vent tank? I understand this needs to be at least a third of the pump head which seems tight on a narrowboat.

 

Stove

-------

I realise there is no convective dump radiator on my plan... is this necessary (could maybe put mushroom vent directly above header tank if in cupboard)?

 

Rads/Heat Exchanger

----------------------------

Is the diesel heater (probably webasto type when funds/scrap salvaging time allows!) likely to be capable of running rad loop to avoid need for heat exchanger and extra pump (maybe an inlne booster pump could be used?)

 

Sorry for so many Q's!!!

 

 

 

gallery_27533_1443_26738.jpg

Opps.... Probably need header return back to the rad loop!!!

Edited by ramblin
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A few thoughts /suggestions

 

  1. I think it is more normal for the engine circuit to feed the calorifier when the thermostat is closed (bypass circuit) and then the skin tank when it opens - so the two are in parallel not in series as you have drawn them
  2. I don't quite see what tops up the radiator circuit.
  3. On my boat I use warm water in the bathroom (as your circuit - using a thermostatic mixer valve) but hot water (ie direct from the cylinder) in the galley. Helpful for boiling kettles, washing up etc, though some risk of scalding.
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Hi scholar Im sure I've found you associated with good info elsewhere on the Web ... Maybe while searching about engine marinisation?

 

I guess this is for safety in case of blockage and since the engine knows nothing about the kind of pressure drop that the cali loop might incur. Though presumably yhis arrangement would need another thermostat on it to ensure engine gets up to temp quickly. Maybe a good option to avoid having to drill into the head before the thermostat would be to use a tee out of the engine outlet with one going to the cali and the other to skintank by way of thermostat.

 

Forgot the header return.

A mixer bypass for galley sounds great!

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Regarding engine cooling/calorifier coil connections - It might depend on your chosen engine/mariniseation setup - it is not

unusual (certainly on automotive derived engines) to use a connection designed to feed the vehicle heater as the feed for

the calorifier, this is not ideal however because it connects to a point on the engine before the built in thermostat and can

cause the engine to take a long time to come up to temperature as you noted. In my case (BMC 1.8 with "home made"

water cooled manifold) I was able to fit a T onto the water outlet from the manifold and then use IIRC a thermostat for

a volvo saloon which fitted into the hose on the skin tank side of this T, with its sensing bulb protruding into the body

of the T, this additional thermostat was also chosen to have a higher opening temperature than the standard one.

 

Thus

Start cold engine-both stats closed - internal circulation only

warm up till standard internal stat opens - external circulation will only be through calorifier coil

when return water from calorifier starts to get warm this will lift the water temperature enough

to cause the additional stat to open and allow circulation around the skin tank

 

I think I was lucky and the standard 82C internal stat works well with the 86C external one

 

springy

Edited by springy
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Regarding engine cooling/calorifier coil connections - It might depend on your chosen engine/mariniseation setup - it is not

unusual (certainly on automotive derived engines) to use a connection designed to feed the vehicle heater as the feed for

the calorifier, this is not ideal however because it connects to a point on the engine before the built in thermostat and can

cause the engine to take a long time to come up to temperature as you noted. In my case (BMC 1.8 with "home made"

water cooled manifold) I was able to fit a T onto the water outlet from the manifold and then use IIRC a thermostat for

a volvo saloon which fitted into the hose on the skin tank side of this T, with its sensing bulb protruding into the body

of the T, this additional thermostat was also chosen to have a higher opening temperature than the standard one.

 

Thus

Start cold engine-both stats closed - internal circulation only

warm up till standard internal stat opens - external circulation will only be through calorifier coil

when return water from calorifier starts to get warm this will lift the water temperature enough

to cause the additional stat to open and allow circulation around the skin tank

 

I think I was lucky and the standard 82C internal stat works well with the 86C external one

 

springy

 

Awesome insights thanks :) that tee must have been pretty big! I didnt consider that it would have to be in the flow to work properly or that it would probaby take a lot of effort (or luck) to tune correctly (enviasge messing around with a kettle and some shims now!). Was it stable over time?

 

Im not sure about the marinisation thing (would probably wind up with ECU based engine if i do go that route as i doubt there are many decent BMC's lying around these days) though there may not be much choice in the matter!

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<snip> that tee must have been pretty big!<snip>

 

Not really - the relatively short piece of hose joins the T to a piece of 35mm copper off to the skin tank and I think the T was actually

made from a short piece of 1 1/2" or 1 3/4" tube, with a piece of 1/2" brazed onto the side as the feed connection for the calorifier.

 

the thermostat looked like this

 

http://www.ebay.co.uk/itm/VOLVO-340-360-1-4-GATES-Thermostat-coolant-83-86-23425-/311539462224?fits=Car+Make%3AVolvo%7CModel%3A340-360&hash=item488932f050:g:RKgAAOSwstxVXlSR

 

which shows it as having an O.D. of 42mm so would lodge firmly in the hose, it would be even better if the sense bulb protruded

further into the T, but it certainly makes a difference and it was available.

 

springy

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Oh god... sorry penny dropped. 82C and 86C is the temp rating that they open at. Doh! So its a case of checking what temp the internal opens up at and adding 5-10 deg for the skin tank one. Maybe a short half section of 15mm could be brazed to it if need be, but still sounds like it may need some setting up to get it opening at correct temp.

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Its probably more a case of availability - whilst thermostats will each have a design open/close range and in theory any physical

shape/mounting design could be made in combination with any design open/close range, in practice you may have to

take what you can find - the one I linked to is an 83c - which will match the engine it was designed or specified for.

You may have to look round a bit to find a higher rating.

In my case it literally was "what was to hand" - the stat had been given to me by a friend clearing some junk as "is

this any use to you ? - have it if you want it" and my response was "Actually that might be just the thing I've been

looking for."

It worked for me, possibly it could work better, but I don't think I'd try and be too "greedy".

 

springy

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How about using a thermal store? Would have the advantages of bringing all the heat sources together, takes car of the vent,feed and expansion of the solid fuel, diesel heater and rad circuit.

 

Another benefit would be that you could do away with the heat dump and pump for the solid fuel.

 

 

post-25003-0-98364900-1477708489_thumb.png

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How about using a thermal store? Would have the advantages of bringing all the heat sources together, takes car of the vent,feed and expansion of the solid fuel, diesel heater and rad circuit.

 

Another benefit would be that you could do away with the heat dump and pump for the solid fuel.

 

 

attachicon.gifScreen shot 2016-10-28 at 04.55.17 b.png

 

Hi Jon,

 

Many thanks for help, this system is certainly simpler and would meet all requirements. I had considered such an approach but went for the calorifier because i've never heard of nor could find a thermal store system sized for a boat (they tend to be hundreds rather than tens of L capacity), though a TS is sized for heat storage capacity rather than amount of hot water available, and perhaps a long thin vessel in cupboard may provide an adequate temp gradient without being too large.

 

The other problem that i thought may be present in this system could be galvanic corrosion due to so many connected systems, though this may also be the case for my 2nd plan too, and presumably the whole thing would need to be filled with antifreeze. All in all it seemed a strange system for a boat but would be great if its is workable.

 

I've checked the webasto thermo top C documentation and although it doesn't detail the pumps maximum pressure it lists the rated flow 450l/hr at 0.13bar so if this is its maximum working head then 60cm or so should be adequate header elevation elevation for the header tank. Though im not sure!

 

In regard to gravity dump radiator maybe one could be installed close to the stove with thermostat similar to springy's skin tank system?

Edited by ramblin
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