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davivid

Combine a Webasto and Alde in the same CH circuit?

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Hello,

 

I would like to install a Webasto boiler - can I also keep an Alde Comfort 2928 in the circuit as a backup? as shown in the diagram below?

 

Will the Alde Expansion Tank work for both systems?

 

Many thanks,

Dave

 

822474299_CurrentCH.png.477ef3d5e3ea87bb436a297edc8059f5.png

 

156753039_ProposedCH.png.24f1245a70f45cabef20775ff1974a07.png

 

 

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No reason why it should not work, But you may want to incorporate an isolation valve to each appliance so that you are not using one boiler to heat another. It looks like you are adding further radiators, so you need to consult a manufacturer's chart so that you can see that the expansion vessel is sufficient for the new capacity. A new vessel is going to be necessary if the boilers can be isolated.

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4 minutes ago, stegra said:

Are you sure that's how your radiators are plumbed? 

I believe so yes, might have the flow and return the wrong way around but that is what it looks like.

 

2 minutes ago, Ex Brummie said:

No reason why it should not work, But you may want to incorporate an isolation valve to each appliance so that you are not using one boiler to heat another. It looks like you are adding further radiators, so you need to consult a manufacturer's chart so that you can see that the expansion vessel is sufficient for the new capacity. A new vessel is going to be necessary if the boilers can be isolated.

Thats a good point. Do I need a an isolation valve on the flow and return or just one? If just one would the expansion tank still work for both?

 

3 minutes ago, ditchcrawler said:

Looking at drawing 2 how will you get hot water without heating the radiators

I was thinking I would just adjust the valves on the radiators themselves?

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6 minutes ago, davivid said:

I believe so yes, might have the flow and return the wrong way around but that is what it looks like.

 

Ok. That's a one pipe system then. Pretty inefficient but might be alright with so few radiators. If the flow and return pipes are as close as your diagram suggests, and accessible, it might be worth considering changing to a two pipe system. But someone may be along shortly to say it's not worth the effort. 

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49 minutes ago, davivid said:

 

 

I was thinking I would just adjust the valves on the radiators themselves?

dont you think that will be it of a pain when you want hot water and not heating, on drawing 1 I take it you just close the one valve on the radiator circuit ? 

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I have been led to believe that some Alde boilers are very fussy about what metals are in the system, something to do with corrosion, but someone will hopefully know more.

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Your proposed system design is wrong. Add new radiators on the left of your existing system (I am assuming you do have two pipe system and radiators tee into flow and return).Plumb your webasto in series with your alde heater at same location as the alde to avoid radiator balancing problems. If you have to plumb at the other end of the boat then plumb it at the far end of the radiator circuit. If you also have to use seperate pump then balancing radiators will be difficult.

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17 minutes ago, ditchcrawler said:

dont you think that will be it of a pain when you want hot water and not heating, on drawing 1 I take it you just close the one valve on the radiator circuit ? 

Yes it likely would be a bit of a pain, but would be a lot simpler to install...

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1 hour ago, ditchcrawler said:

Looking at drawing 2 how will you get hot water without heating the radiators

 

This is a good example of the sort of unintended consequences of trying to use two heat sources on one system. 

 

They are always a compromise, and the installer is usually hardly realises they've done so. Until they hand it over to another user who immediately exposes all the shortcomings!

 

 

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3 minutes ago, Cas446 said:

Your proposed system design is wrong. Add new radiators on the left of your existing system (I am assuming you do have two pipe system and radiators tee into flow and return).Plumb your webasto in series with your alde heater at same location as the alde to avoid radiator balancing problems. If you have to plumb at the other end of the boat then plumb it at the far end of the radiator circuit. If you also have to use seperate pump then balancing radiators will be difficult.

I've just checked and its definitely a one pipe system

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2 hours ago, davivid said:

I've just checked and its definitely a one pipe system

That's a shame. It'll work, it will just be very manual to get the best output.

 

Does one pipe go up either side of the boat?

Edited by Cas446

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5 minutes ago, Cas446 said:

Does one pipe go up either side of the boat?

I've kind of drawn it in plan. Calorifier is starboard and the radiator opposite port. Both in the galley at stern end.

 

Pipework currently both sides, but in my proposed I've kept it to one side.

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If you can, then convert to a two pipe system with flow and return for both the radiators and the calorifier. No problem with keeping Alde in circuit. Just make sure it can't be isolated so it can provide the expansion. Balancing the radiators will be arkward if alde and webasto are not next to each other and hence the circ pump is at different location. But will work.

Edited by Cas446

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If you're redoing the pipework all on one side you might as well take the opportunity to make it a two pipe system. How much distance is there between the Alde and the proposed Webasto? I'm thinking, if it's not too far you can run 22mm pipes from the Webasto to the Alde legs and fit isolators to each. That will overcome the balancing problems. 

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13 hours ago, Cas446 said:

If you can, then convert to a two pipe system with flow and return for both the radiators and the calorifier. No problem with keeping Alde in circuit. Just make sure it can't be isolated so it can provide the expansion. Balancing the radiators will be arkward if alde and webasto are not next to each other and hence the circ pump is at different location. But will work.

Hopefully that should be ok - as the Alde will only really be used if the Webasto breaks down. I've added a balance valve on the flow of the Alde to reduce the water circulating through it rather than the end radiator?

 

I guess it also has an advantage of adding extra capacity for Webasto to work with too.

13 hours ago, stegra said:

If you're redoing the pipework all on one side you might as well take the opportunity to make it a two pipe system. How much distance is there between the Alde and the proposed Webasto? I'm thinking, if it's not too far you can run 22mm pipes from the Webasto to the Alde legs and fit isolators to each. That will overcome the balancing problems. 

Unfortunately a small section of the pipework is inaccesible without removing the shower.

 

1246164739_ProposedCHv2.png.f815e1f44dc0cfc52e51b08b9c74ca65.png

 

 

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17 hours ago, Detling said:

I have been led to believe that some Alde boilers are very fussy about what metals are in the system, something to do with corrosion, but someone will hopefully know more.

The 3xxx series should not use copper plumbing parts say or said Alde because of corrosion of the aluminium heat excharge. No such stipulation with the tall 2xxx series that use a steel heat exchanger (I think).

 

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1 hour ago, Tony Brooks said:

The 3xxx series should not use copper plumbing parts say or said Alde because of corrosion of the aluminium heat excharge. No such stipulation with the tall 2xxx series that use a steel heat exchanger (I think).

 

That's good because there are a few copper and brass parts, but mostly plastic pipes. I also assume the calorifier is copper, and the radiators steel.

1 hour ago, Cas446 said:

That's better.

Great thanks!

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2 hours ago, davivid said:

Hopefully that should be ok - as the Alde will only really be used if the Webasto breaks down.

 

In which case, one (not two) isolation valves on each of the boilers will probably suffice. Run the system with the Alde turned OFF isolation valve closed most of the time. Then when the webby breaks down, turn it OFF, close its isolation valve, open the Alde isolation valve and start the Alde. 

 

The only possible problem I foresee with this is the two boilers are at opposite ends of the system, so the balancing set up for one boiler will be the opposite of that needed for the other. Probably won't matter with a one pipe system.

 

 

Presumably the Webby has a circulating pump built in? 

 

 

 

 

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37 minutes ago, Mike the Boilerman said:

The only possible problem I foresee with this is the two boilers are at opposite ends of the system, so the balancing set up for one boiler will be the opposite of that needed for the other. Probably won't matter with a one pipe system.

What are the advantages of a two pipe vs one pipe system?

 

38 minutes ago, Mike the Boilerman said:

Presumably the Webby has a circulating pump built in? 

Yes - I'd imagine a better one than the Alde.

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3 minutes ago, davivid said:

What are the advantages of a two pipe vs one pipe system?

One-pipe system.

Hot water goes into the 1st radiator, cools (gives off heat via the radiator) and the now cooler water exists and proceeds to radiator no2, the water is further cooled, and the now quite cool water exits radiator no2 and proceeds to radiator no3, by now the water is quite cool, it enters radiator 3 and fails to even get the radiator warm. The water exits radiator 3 and heads back to the heat source.

 

Two-Pipe system

Hot water enters radiator one, the water cools and leaves the radiator and goes into the 'return', Radiator No2 is also connected to the 'hot-feed', takes the water and as the water cools it leaves and goes into the return, Radiator No3 is also connected to the 'hot-feed', takes the water and as the water cools it leaves and goes into the return, 

 

 

With a one-pipe system the water gets progressively cooler as it is fed into the next radiator.

With a two-pipe system each radiator get hot water.

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On 13/10/2019 at 11:44, Alan de Enfield said:

With a one-pipe system the water gets progressively cooler as it is fed into the next radiator.

With a two-pipe system each radiator get hot water.

 

On 13/10/2019 at 11:49, Mike the Boilerman said:

A two pipe system works, a one pipe system doesn't. 

 

Great so I've got a good design now, other than having separate circuits for heating and water. 

 

Thanks all

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