joining two calorifiers in perfect matrimony

[stegra]

5 hours ago, Tash and Bex said:

Lol, have to say "grubby days" are few, there is plenty in the existing system for a shower, so really it is only the two calorifiers for a bath, however if the heat is "free" ie engine or solar, I'd rather have it.

 

When it is just the webasto running, I just want to heat the minimum of water.

liking this a lot, strikes me that I could make use of the coils in the vertical calorifier, rather than the replacement coil in the left one. the temp would be evened out by the circulation surely? the pump would only circulate when either the engine was running, or the solar was producing heat.

 

not sure I would need any non return valves at all? wouldn't water pressure prevent mixing??

Yeah. The NVRs are probably not necessary, as I mentioned. If you use a solar circulation pump to circulate the water, you'll need an NRV in that circuit to prevent the cold water bypassing the tanks when a hot tap is open. A clack valve would offer least resistance.. I've just tried blowing through one of those pumps and there's no resistance at all. 

 

I'm not sure why you would only run the pump when the engine or solar is working. I would run the pump whenever I wanted a bath, regardless of the heat source. All other times I would just heat one calorifier. I know pretty much nothing about solar water heating so not sure if it's realistic to fully heat two calorifiers from what will probably be a modest sized collector. From what I've seen in Turkey, Greece etc. they appear to have a large collector angled to the sun for a moderately sized tank... And a warmer climate. Maybe someone with some experience will be along with what's achievable. 

 

The only time at looked into solar water heating was when I built my motorhome. The issue then was how to prevent boiling, but that was only going to be a 10 litre tank. If boiling could be a problem, the pump could be thermostatically controlled to circulate at a given temperature. 

[David Mack]

 

10 hours ago, Tash and Bex said:

 

liking this a lot, strikes me that I could make use of the coils in the vertical calorifier, rather than the replacement coil in the left one. the temp would be evened out by the circulation surely? the pump would only circulate when either the engine was running, or the solar was producing heat.

 

In a conventional hot water tank the water is stratified, hot at the top and cold at the bottom. So only a short while after you put the heat source on, you can run some hot water off (but not a bathful). But if you have a circulating pump running then instead of a calorifier half full of hot water and half full of cold water, you will have a whole calorifier full of lukewarm water. True if you wait long enough you will have a full tank of hot water either way, But if you can't draw off a little hot water for things like hand washing or washing up you have lost something.

Edited September 30, 2019 by David Mack