Replumbing Calorifier

[cuthound]

Hi all,

 

We have recently completed our maiden trip in Delta Queen, bringing her from Ventnor Farm Marina to our home mooring on the Coventry Canal.

 

Excellent trip, and apart from a heavy shower whilst descending the Hillmorton locks brilliant weather.

 

On the trip we noticed that the radiators were getting hot, even though the Webasto heater was switched off.

 

When we got to our home mooring I looked at the calorifier plumbing connections and think they are plumbed incorrectly. The calorifier is a "Surecal" and was replaced in January. It has 6 connections. Lets call them 1 to 6 starting with 1 at the top.

 

The bottom one (6) is the cold feed in, the top one (1) the hot water out, and the other 4 are the twin coils for the engine cooling circuit and the Webasto heater circuit. I think that the two coils are connection 2 & 3 and 4 & 5.

 

Currently the engine circuit is connected to 3 and 4, and the Webasto heater to 2 and 5. I think this connect the engine and the Webasto in series, hence the hot radiators when the engine is running. (The rads also get hot with the Webasto only on).

 

I think the engine connections should be on 4 and 5 , and the Webasto heater on connections 2 and 3, as this will allow the engine to heat the hot water, but not the radiators. Am I correct?

 

Once I have identified the correct connections, how easy is it to change them? I presume you have to drain the calorifier and also the engine and radiator circuits.

 

If they are plumbed incorrectly, my first port of call will be to ask the company that installed the calorifier to sort it out free of charge.

 

Thanks in advance for the help[.

 

Alan

 

 

[NMEA]

On the face of it, from your description it appears your diagnosis is correct, though of course this depends on just how the calorifier coils are arranged, certainly it would be most unusual if one coil was not 2 & 3 and the other 4 & 5. Rectification is pretty simple though, especially if they have used heater hose for the final connection section as I do as you can compress the hoses and only loose the small amount of coolant contained in the coils. One final point if the Webasto is involved in the engine coolant circuit then it's circuit needs the anti freeze strength reducing to 25% from the probable current 50% after rectification to get optimum heat transfer. Of course all this may be wrong and some convection circulation may be occurring with the Webasto circuit removing heat from the calorifier water to its coolant via the coil but it certainly needs investigation, perhaps you can advise the precise model of Surecal you have?

Edited June 15, 2014 by NMEA

[MtB]

If the engine and the webby are in series as it sounds, when you fire the webby and heat the rads, the engine will be heated up too. The water pump hose connections will probably be the first bits to get warm.

 

Wait until the engine is cold then try this. It will confirm or contradict your diagnosis.

 

MtB

[BEngo]

All good stuff above. No need to drain the domestic hot water out of the calorifier if/when you swop the coil connections. To be really safe switch the water pump off and open a hot tap till the flow stops to de-pressurise the calorifier.

 

N

[Paul C]

If you do go from a single heating circuit to 2 circuits, you'll also need to plumb in a 2nd header tank. There's an advantage in having the radiators fed by the engine coolant though, so if it works okay it would be worthwhile leaving it as a single circuit. I suspect the Webasto will waste diesel (ie warmth from the radiators will be low initially, then rise) due to having to heat up the engine too, which is the disadvantage.

 

I'm not sure if some complex kind of valving could be used to "shut off" the engine from the circuit, and if its able to do this, you're back to needing 2 header tanks again etc to allow for expansion and contraction of the coolant's volume.

[MtB]

Good point about the need for a second header tank. Avoiding fitting one is probably the whole reason for this weird circuitry in the first place. It's probably anything but a installation error.

 

MtB

[BEngo]

A brace of Tee pieces in the outlet and inlet from the header tank would enable one tank to feed both systems. It's coping with the expansion of the whole system now, and as two systems would not get significantly larger (more water to expand) so there should be enough capacity.

 

N

[NMEA]

A brace of Tee pieces in the outlet and inlet from the header tank would enable one tank to feed both systems.

That would link the systems and mix the coolants, a situation the OP is trying to reverse, best method is to fit a pressure vessel in the Webo circuit, they always perform better and more reliably that way, I haven't fitted one with a header for some time now.

[Paul C]

That would link the systems and mix the coolants, a situation the OP is trying to reverse, best method is to fit a pressure vessel in the Webo circuit, they always perform better and more reliably that way, I haven't fitted one with a header for some time now.

 

Our boat has central heating via the engine coolant and HAD a back boiler (so the dreaded 2 heat sources supplying one system - the pipework ran through back boiler, calorifier, radiators and engine). Needless to say, with the radiators on, the water takes an age to heat up but its nice to have the "free" heat for the radiators. We never used the back boiler and replaced the stove with one without.

 

We are upgrading boats soon and one of my considerations is to generate hot water (enough for a decent shower) without running the engine, since we will be living on board and need showers in the morning etc (and don't want to run th engine too much - we'll have a significant amount of solar power too). So one of the requirements is a decent central heating system which can heat the water (probably via a 2nd coil on the calorifier) and radiators (via a 'summer valve' or at least some way to shut down all the rads and just heat water). BUT I'd like to also incorporate radiator heating via engine coolant. Is there a logical way to do this and avoid the eg Webasto diesel central heating heat up the engine block in the morning needlessly? Either via some arrangement of valves, or possibly keeping it simple by installing more radiators and extending the entirely independent engine coolant circuit to heat these too?

[NMEA]

Physically simple to attain a single split circuit with T port valves isolating each heat source but still means the whole antifreeze system will need to be 50% which does mean the Webasto is slightly less efficient due to the increased level of glycol which becomes a poorer carrier of heat the higher the concentration. Another way would be to use a heat exchanger in the circuit but it then becomes expensive and space hungry.

Edited June 15, 2014 by NMEA

[cuthound]

Hi all, thanks for the advice given so far.

 

What a fantastic resource this forum is.

 

Third time lucky, my two previous attempts to post this from my tablet failed, even though all seemed normal after hitting the post button. So if I end up with multiple posts, please accept my apologies in advance.

 

As advised by MtB, I used the Webasto without starting the engine, and it confirms that the engine and heater are in series, as the hoses get warm.

 

I also established that there is only one header tank, which is connected to the cold (return) side of the Webasto.

 

The Kingsground manual clearly states in the heating system overview that the engine and Webasto are connected to individual calorifier coils, so I am tending towards the opinion that it is a wrongly fitted replacement calorifier. However this doesn't explain the lack of a second header tank and on her maiden (for us) voyage I recall that the needle on the water temperature gauge was ion the vertical position, which I assumed to be indicating "normal" temperature.

 

I have a few questions, which hopefully the forum can help with, before I decide what to do:

 

Will the engine be overcooled, by feeding the radiators and the keel cooler?

 

Is the water pump on the Beta 43 stressed by having to pump water around the radiators as well?

 

Is the water pump on the Webasto stressed by having to pump water around the engine as well?

 

If the consensus is that there is a low probability of long term damage, I may leave it as it is.

 

If not, then I will replumb, using the existing header tank for the engine, and using a pressure vessel for the Webasto as suggested by NMEA. If so can anyone recommend a suitable pressure vessel?

 

Thanking you all again in anticipation.

 

Alan

[Tacet]

We are upgrading boats soon and one of my considerations is to generate hot water (enough for a decent shower) without running the engine, since we will be living on board and need showers in the morning etc (and don't want to run th engine too much - we'll have a significant amount of solar power too). So one of the requirements is a decent central heating system which can heat the water (probably via a 2nd coil on the calorifier) and radiators (via a 'summer valve' or at least some way to shut down all the rads and just heat water). BUT I'd like to also incorporate radiator heating via engine coolant. Is there a logical way to do this and avoid the eg Webasto diesel central heating heat up the engine block in the morning needlessly? Either via some arrangement of valves, or possibly keeping it simple by installing more radiators and extending the entirely independent engine coolant circuit to heat these too?

 

You can achieve both means of heating the radiators by introducing a heat exchanger between the engine cooling and Webasto rad circuits. Usual method would be to put a plate exchanger (c£40 on ebay) in the engine return from the calorifier where (hopefully) with the layout of your boat also allows easy connection to the heating circuit. Near the calorifer in a twin-coil system should be suitable. You will almost certainly need a way of circulating the hot water in the rad system and a 12v pump (centrifugal so as not to impeded the flow when the Webasto is operating) should do the job

[Paul C]

Physically simple to attain a single split circuit with T port valves isolating each heat source but still means the whole antifreeze system will need to be 50% which does mean the Webasto is slightly less efficient due to the increased level of glycol which becomes a poorer carrier of heat the higher the concentration. Another way would be to use a heat exchanger in the circuit but it then becomes expensive and space hungry.

 

 

 

You can achieve both means of heating the radiators by introducing a heat exchanger between the engine cooling and Webasto rad circuits. Usual method would be to put a plate exchanger (c£40 on ebay) in the engine return from the calorifier where (hopefully) with the layout of your boat also allows easy connection to the heating circuit. Near the calorifer in a twin-coil system should be suitable. You will almost certainly need a way of circulating the hot water in the rad system and a 12v pump (centrifugal so as not to impeded the flow when the Webasto is operating) should do the job

 

Many thanks, that's 2 ways and both seem equally valid and about the same in cost.

[smileypete]

 

Our boat has central heating via the engine coolant and HAD a back boiler (so the dreaded 2 heat sources supplying one system - the pipework ran through back boiler, calorifier, radiators and engine). Needless to say, with the radiators on, the water takes an age to heat up but its nice to have the "free" heat for the radiators. We never used the back boiler and replaced the stove with one without.

 

We are upgrading boats soon and one of my considerations is to generate hot water (enough for a decent shower) without running the engine, since we will be living on board and need showers in the morning etc (and don't want to run th engine too much - we'll have a significant amount of solar power too). So one of the requirements is a decent central heating system which can heat the water (probably via a 2nd coil on the calorifier) and radiators (via a 'summer valve' or at least some way to shut down all the rads and just heat water). BUT I'd like to also incorporate radiator heating via engine coolant. Is there a logical way to do this and avoid the eg Webasto diesel central heating heat up the engine block in the morning needlessly? Either via some arrangement of valves, or possibly keeping it simple by installing more radiators and extending the entirely independent engine coolant circuit to heat these too?

 

That could be a bit of an ask, there are a couple things to bear in mind:

 

1). It needs to avoid overcooling the engine while heating calorifier/rads as can cause premature wear and engines don't come cheap, usually!

 

2). It needs to avoid under-loading the diesel heater while heating calorifer/rads, as this could cause 'short cycling' of the heater with greater chance of maintenance and reliability woes.

 

On a topic a while back I came up with a scheme for direct heating of the calorifier via a heat exchanger but without 'overcooling' the engine, someone made it and they seemed quite happy with it :

 

http://www.canalworld.net/forums/index.php?showtopic=55788&page=1#entry1058793

 

It should be straightforward to add a diesel heater in parallel with the engine feed on the engine side, but stop unwanted reverse flow through the engine (or heater) with light non return valves such as 'swing check valves'.

 

The radiators could be put in parallel with the heat exchanger on the engine side too but with some way to switch them off until the engine is fully up to temperature (or switch off altogether in summer).

 

Or if you don't want to have the radiators sharing the engine coolant circuit, another heat exchanger (and pump) could be added, maybe in the way Tacet has mentioned above.

 

cheers, Pete.

~smpt~

Edited June 17, 2014 by smileypete

[NMEA]

Webasto actually list all the thermostatic valves to achieve just what is being talked about here i.e. the engine taking over from the Webasto when the Webasto senses its temperature is lower than the engine coolant temperature and vice versa. It is however, designed for pre heating truck engines and or for supplemental heating until engine temperature is reached which though in theory precisely what is required here is also not really designed for long usage (normally only until the coolant is up to 75 deg and then turned off) and is relatively inefficient as of course the A/F is all at the motor strength (say 50%) which is less efficient at removing heat from the Webasto to distribute throughout the heated loads. This not only means that the radiators will be less efficient but as the heat exchanger is cooled less at higher temperatures it will cycle more and require more frequent servicing. It will work, but at a cost, one could of course reduce the ratio in the whole thing to 25% using Alpine Anti Freeze from Millers Oils which has enough inhibitors and will protect down to -13 degrees.

Edited June 17, 2014 by NMEA