plumbing a twin coil calorifier

[Justin]

well i got a deal on a surejust calorifier twin coil, so my stove installation is on hold for a mo until i make up my mind about all your interesting posts!!

 

This post is for a little advice on plumbing a calorifier, it has twin coils as i hope to fit a webasto boiler, is it ok to leave one coil for the time being until i am ready to fit the webasto?

 

and can someone just confirm i have the right idea withnthe plumbing,

 

1) The cold water is pumped back to the calorifier cold fill, on the way do i tap off for cold water points ?

 

2) the hot feed out of the tank is then split in to two one for hot water, one fro radiators?

 

 

ok so where does the webasto plumb in or does that just heat one of the coils on a closed system.

 

the knowledge of the forum is greatly appreciated

 

 

Justin

[Gary Peacock]

Hi Justin,

 

The Webasto and radiators via one coil are a closed circuit.

The 2nd coil is a closed circuit with engine coolant.

Feeds normaly at the top and outlets at the bottom.

The cold feed can be tapped before the inlet.

Cold feed to the bottom outlet to the top.

Pressure relief blow off over the side.

 

Don't forget antifreeze in closed circuits!

 

Hope this helps

 

Gary

[Justin]

Thanks gary, that makes sense so the webasto and the radiators are closed on one coil and hot water on the other. that explains the header tank with webasto,

 

cheers

 

justin

[Martin]

I'm glad you understood that Justin!

Gary got me a little confused!

 

Calorifier has two coils - Yes you can leave one unconnected - water is not going to flow out of the holes!

 

The water heated by the Webasto flows from the Webasto and through one coil - passing through radiators before and after, before returning to the Webasto.

No pressure release valve is required in this circuit if you have a header tank (which should be the highest point of the system to avoid airlocks).

Incorporate a drain point at a convenient location in case you need to get the water out at any time.

 

The other coil is fed from the engine cooling circuit which might be straightforward if you have a newish engine designed with take-off points for a calorifier.

If it doesn't - like mine - you need to improvise!

This gets a little complicated because you need to place the engine thermostat in the circuit so that the engine heats itself and the calorifier BEFORE it opens to send water through the skin tank - otherwise you will wait hours for your hot water!

 

The water to the calorifier from the fresh water tank is as you suggest just a spur off that feeding the cold taps.

This feeds the calorifier tank at the bottom!

The water is heated and then comes out the TOP outlet of the calorifier.

This pipe has a pressure release valve in it which allows for the heating water to expand in the tank.

This will start to drip as soon as the heating starts and so should be vented overboard (preferably) or into the bath or basin.

Hot taps are then provided at points after the release valve.

 

Sorry Gary if I have just reiterated what you have already said - it was just the "feeds normally at the top" bit that I thought confusing.

You wouldn't want to confuse this with the fresh water feed to the tank.

[ChrisPy]

some stove suppliers recommend large diameter heating coils in the calorifier. For example, Harworth (Bubbles) recommend 28mm if gravity convection circulation is used.

The calorifier suppliers talk about 1/2" connections, or 3/4" as a special. As Harworth state, that is just the connection size. It does not imply the coil is 3/4".

Can anybody recommend a calorifier manufacturer who is prepared to fit large diameter coils? 28mm preferably?

[stuart]

I'm looking to plumb in a twin coil unit as well.

 

Due to pipe work restrictions looks like I'm going to need to use a pump for the central heating/coil from a stove.

 

What pumps do people use - do you have to be careful about these overheating? How noisy are they?

[Richard Bustens]

Hi

I think what you need is a high-gain type, that most advertise , it is not just the bore of the pipe but also longer on one of the twin coiles

[rog guiver]

The last boat had a squirrel that convected through one radiator and pumped through the other two.

 

The pump was rather noisy so, after a lot of spade wark I purchased a Bolin pump (EVP500) from Kuranda Marine (01663 734800).

 

It was so quiet that when I sold the boat (with a new shell on order) I replaced the pump with the "noisy" one and have now installed the Bolin in the new boat.

 

With regard to the twin coiled calorifier I routed the alde boiler through the top coil and the engine through the bottom one. Also the return from the bottom coil went back to the engine through a towel rail.

 

The reason for this layout was that obviously, assuming the coils within the calorifier are at different levels, the bottom coil would heat up more water than the top one. So, as the main heat was supplied from the engine and the Alde "topping up" the calorifier in the morning it seemed sensible to connect the engine to the bottom one.

 

 

Out of interest, on the new boat, I connected a temperature sensor in the calorifier about half way up the side (spare connection) and even though the immersion heater produces water at about 80C (at the top)the temperature half way down the calorifier only reaches 30C! I will be very interested to see , once the boat is in the water, with the engine supplying the heat lower down in the calorifier what temperature reading I get.

Edited October 29, 2004 by rog guiver

[Richard Bustens]

Hi

Mine has two inlets at top and two outlets at bottom with both pipes running from top to bottom

[John Orentas]

Hi Richard.

 

Are you sure about that ? That sounds unusual, I asssume you do not include the heated water in /outlets. Check by blowing into them and see where air comes out. Not that I know much about these things.

 

John Squeers

[Richard Bustens]

Hi John

http://www.jabscoshop.co.uk/item.asp?sid=5...er+pump&id=3396

Water in is just visable on the right bottom water out ot top , then the 4 pipe holes you can see are left the bigger coil and right the smaller one bottom out top in

[John Orentas]

Hi Richard.

 

Looked at the picky, seems to me the top two fittings on either side of label for the top coil. Bottom two directly below for the bottom coil.

 

Very top water out, couldn't see water in.

 

John Squeers

Edited October 29, 2004 by John Orentas

[Richard Bustens]

Hang on John it's only in the garage waiting to go to boat i will go and blow down one!!

[Richard Bustens]

Hi John

Right looking at the pic there are 4 conections clearley visable

If i blow in the top left the air comes out of the bottom left and if i blow in the top right it comes out of the bottom right.

If you look cairfully on the extreem right you can see the edge of the inlet neer the bottom and above that there is another point neer the top as well as the hot out on the very top if i blow in the top it comes out of both of the side ones and i think the top one is for presure relife valve as i have just found one in the box.

So the left pair top and bottom are further apart than the right pair meaning that the left is the high-gain side and the one i presume i connect to the ebberspacher?

[Big COL]

Richard

 

I have the fitting instructions for c-warm with me, and the connections are described as follows. As you look at the tank with the immersion looking at you, same as picture on the web site.

 

1- connection (A) this connection is at the very top of the tank and is = hot water outlet

 

2- connection( this connection is bottom right of the tank and is= cold water inlet

 

3- connection (C ) this connection is top right of the tank and is = relief valve

 

4-connection (D1) this connection is two thirds up the tank on the left and is = coil inlet.

 

5-connection(D2) this connection is below (D1) on the left and is =coil outlet

 

6-connection(E1) this connection is two thirds up the tank on the right and is coil inlet

 

7-connection(E2) this connection is below (E1) on the right and is coil outlet

 

8- connection (F) is the immersion heater

 

 

 

D1/D2 is one coil and E1/E2 is the other coil. As far as I can see both coils are equal size as it states. The coils of c-warm heater are completely independent in operation. the water storage heater will work satisfactorily with either coil alone or with both coils together in use.

 

Hope this helps any more info required I am only to happy to help

 

Colin

Edited October 29, 2004 by Big COL

[Richard Bustens]

Thanks Colin

I spose i have the same directions someware in the box but i have not opened the plastic bags as yet.

But the point i think i was trying to make is that the points are top to bottom not side to side giving overall heating of the water in the tank not top heating on one coil and bottom heating on the other. or at least on this type of tank anyway,

Was just thinking if Rog has connected the wrong way round it would still probably work but take a lot longer to heat up as he would have connected the two systems together, in a big double s

Edited October 29, 2004 by Richard Bustens

[Big COL]

Richard

 

If its a horisontal tank some have one coil above the other.

 

colin

[John Orentas]

Richard.

 

In practise I doubt if it would matter much, the hot water would find it's way to the top of the tank by convection. What could make a differance, the hot water would cover the lower coil and later the higher one. Any thermostats in the supplies from stove or engine could cut out prematurely.

 

Thinking more about it, the heating coils would be more effective if they were situated as low as possible.

 

John Squeers.

[timboharticus]

I have seen it suggested that a non-return valve nrv be fitted to the cold feed.

 

This reduces heat losses into the cold water pipe.

 

This is more of a problem on horizontal calorifiers.

[Martin]

I think that might have been my suggestion - at least on the forum!

 

The main reason for this is that it saves you having to drain the calorifier tank if you want to work on the pipework anywhere else in the system.

Without it, the calorifier will act like a header tank.

You might want to work on the pump for example.

You can turn off the stopcock to the main freshwater tank but with no non-return valve, you will still have gallons of water ready to drain from the calorifier into the cupboard under the sink (or wherever your pump is) when you undo a pipe.

 

A non-return valve is also placed in the hot water supply from the engine.

This is there to stop the hot water in the calorifier keeping the engine nice and warm by circulating by convection after you turn it off.

[Pinkatpole]

With adding a non return valve to the cold water feed which is best practise, you may also need to add a small expansion tank after the valve, as the system will not be able to use the cold water accumulator as an expansion point.

 

With the non return valve there is no room for the hotwater to expand into as it is heating. It will only take about 15 minutes heating before your pressure relief valve starts its annoying drip as the pressure will try to increase above 3 bar.

 

A 5 litre tank is sufficient for a 13 gallon calorifier.

 

If you put an isolation valve before the expasion tank its a perfect place to enable draining the calorifier from, for wintering, maintenance etc

[Martin]

I thought this was a good idea - for a while!

Won't such an expansion tank be pressurised from the water pump anyway?

This won't leave much additional expansion room for the function you describe.

Would an ordinary "accumulator" be suitable for the purpose?

Are they rated to this pressure?

[Pinkatpole]

I thought this was a good idea - for a while!

Won't such an expansion tank be pressurised from the water pump anyway?

This won't leave much additional expansion room for the function you describe.

Would an ordinary "accumulator" be suitable for the purpose?

Are they rated to this pressure?

<{POST_SNAPBACK}>

 

Martin

 

The coldwater accumulator next to the pump will take the pressurisation from the pump. The problem with adding a non return valve to the cold water fill to the calorifier, means that once the system is fully pressurised, as the hot water expands as it is warming, there is no where for the expansion to go if the non return valve is fitted. If it was not fitted it would use the cold water accumulator to accomodate the thermal expansion of the water. You therefore have to add another one. Water expands approximately 4% when heated between 25 and 75 degrees C.

The expansion tank is exactly the same as the accumulator but with a diaphragm that has a higher temperature rating, approx 90 degrees C than the cold water accumulator. They are generally rated at 10 bar, but on installation must be set at the cut off pressure of your water pump. The cold water should be set at 5psi greater than the cut off pressure off the pump.

 

On my boat without the expansion tank the pressure increased from 20 to 45 psi in less than 2 minutes once the water temperature reached 50 degrees C.

[Martin]

Cool!

And where does one find such a thing - I assume it is something that is generally fitted to home central heating systems?

I don't recall seeing them in chandlers.

[Pinkatpole]

Cool!

And where does one find such a thing - I assume it is something that is generally fitted to home central heating systems?

I don't recall seeing them in chandlers.

<{POST_SNAPBACK}>

 

Got mine from Sawley Marina, Nottingham. Maker is Cleghorn Waring. Part no is CW385 for a 5 litre tank. This is big enough for a 60 litre calorifier with a water pump cut out pressure of 20psi.

 

Cleghorns are specified for both purposes, expansion and accumulator.

 

Ive just checked the website and you can buy it online £24.95

 

Info at www.cleghorn.co.uk under Pressurised water systems