wamsler to thermal store height difference

[stormmorris]

Hi 

 

I am new to this site as a member not sure if to post this in here or other sorry. I will explain what I have and what i was going to do any advice more than welcome or opinions.

 

Two years ago after buying a house i purchased a used thermal store very cheaply that had been ripped out of a newly renovated house as they wanted to change the heating and hot water situation. Last month i found a wamsler k148 cheaply again and in very good condition. I wanted to connect the two via a thermosyphon, the thermal store weighs 800kg when full and is too wide to pass any of the old stone door ways bar the one in the kitchen!

 

I was going to mount the thermal store next to the wamsler at 400mm the height differences would be between the flow 700mm and the return 300mm. I can add another 400mm to both by raising the store on a block plinth alternatively I can open up the ceiling adding another 300mm to the 400mm but I rather not. I was advised by one person that even sat on the ground it would function but i would love to know if anyone has any other opinion. I am a lover of science and I understand that the principle is the relative density difference between the cold and hot water that enables it to function  thus the more height difference on the cold side the larger the difference in density but that being said what are the minimums (most peoples answer is should work) but if anyone can help me with a more solid answer based on experience or knowledge that would be fantastic.

 

Thank you for reading

[PeterW]

Welcome

 

By what you’re describing you mean that the store upper connection would be 700mm higher than the boiler output, and the input 300mm higher ..?? Doesn’t seem to make sense ..?

 

A thermosyphon will work happily at 2-300mm head, it’s an upward flow due to heat and will happily pull water up a couple of storeys. If the store weighs 800kg then I guess it’s around 600 litres..?? That’s a big store and a lot of water to heat. 

 

If you check the instructions for the stove it is not guaranteed to run on an unpressurised circuit and should have a circulation pump, heat dump circuit and heat exchanger - I take it you didn’t get any of this lot with it..??

[stormmorris]

Hi thank you for your reply, what i meant was that the hot side of my alleged thermosyphon would have a difference of 700mm and the cold (return from tank back to boiler) would only be 300mm. it is a  large store yes but it uses two tanks one inside the other each 300L in volume the internal one giving direct hotwater. the stove has and alternative that is not fitted as standard for protection in event of over heating but I wasnt aware that anyone would make an uncontrolled heat source such as a cooker only dedicated to use a circulation pump

[PeterW]

My guess then is it’s an AVC Smartline which is actually classed as a UVC under the regs as the water in the inside tank is at mains pressure not gravity pressure.....

 

They need a lot of other kit to make them legal to install - control set, expansion vessel and decent discharge pipework to begin with.

 

You could get a decent thermosyphon going but tbh I would stick a £50 pump and pipe stat on the pipework and boost the flow between the two. If it fails then it will still thermosyphon but you will need to add a metal header tank to the set up as a plastic one will be unsafe.  

[stormmorris]

yes it's the avc smartline I did chat with the guy at avc in there technical department who said there was no reason why I couldn't run the main body of water round the dhw tank on low pressure with a header tank would that stop it being classed as an unvented cylinder? Then I was going to use appropriate size expansion vessel on the dhw side. I am also in the process of acquiring 12sqm of solar thermal and am going to hook up my oil boiler to the tank 

[PeterW]

You may struggle to get decent water flow out of the AVC in that setup and as long as there is an open pipe to the header you won’t need any expansion vessels. You will however need a pair of headers - one potable, one heating, so there will be a fair bit of pipework to do to an attic. 

 

Has the AVC got a backup immersion in it ..??

 

Solar thermal needs a pressurised flow circuit with glycol in it so you will need to use a plate heat exchanger with the AVC as you can’t mix the boilers and the solar thermal with the same fluids. 

[stormmorris]

Ha thank you for you really quick responses I was going to run the centre all tank inside at mains pressure but the external tank at neutral plumb my wood fire into the direct and the oil in on the coil there is also a coil for the radiators then, there is an immersion heater yes (I was looking at the solar thermal heat exchangers that plug in instead of the immersion?) sorry If I'm not the clearest at explaining. So the dhw tank would be mains pressure 

Edited December 13, 2018 by stormmorris

[PeterW]

I’d use the coil for the oil, one for the solar thermal and plumb the rads and the wood burner into the tank direct as that then provides you with your heat loss circuit which you must have with a wood burning unit. 

 

Also means if you bin off the oil boiler for an ASHP then you’ve got a smaller circuit to fill with antifreeze. 

 

Leave the immersion for emergencies or when you don’t want to run any fossil based product. 

[stormmorris]

That sounds great thank you for your help and time will let you know how I progress