Two into one does it go?

G

Goldspoon

Okay, a three port valve sends water in one leg of the valve and can allow water left or right or left and right out of the other two legs.

Is there such a thing as this...

Imagine the T shape of the valve. Water enters from the top left. Water enters from the top right. The valve can choose which flow to allow down the vertical.

Why?

Well I am looking at the various ways of adding a wood burning stove to a system that already has a combi (feeding rads) but not a modulating combi that can accept preheated water. One way is to direct water from a cylinder (preheated by wood burner) to the valve and to direct the combi to the valve as well. The valve can then be switched between one or the other depending on requirements.

The valve can be manually operated maybe (I can use combi as back up for HW) or maybe even directed by a stat on the cylinder to "switch to combi" if cylinder drops to a given temp.

Apologies if I have made any daft assumptions or points at this stage as this is early research.
 
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i suspect a normal3 port valve could do this backwards. but weather you are aloud to alter the pipe work on your heating system i am not sure. is it pressurised?
 
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from a cylinder (preheated by wood burner) to the valve and to direct the combi to the valve as well.
Be careful not to have mains pressure meeting gravity fed water , or it WILL push it backwards.

A 3 port valve doesn't work well backwards, they "let by" that way round. You could use 2 x 2 ports the right way round, except that they aren't designed for mains pressure! Check their specs.
 
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i was mearly thinking abotu the fact a normal person is not aloud to work on a unvented system, so maby that you proposed to do may not be legal(?) you are probably more than capable of designing something that will work as are some people. ;)
 
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what about two 2 port valves controlled from a stat on cylinder
 
G

Goldspoon

i was mearly thinking abotu the fact a normal person is not aloud to work on a unvented system, so maby that you proposed to do may not be legal(?) you are probably more than capable of designing something that will work as are some people. ;)

I believe that one is allowed to work on the pipes etc. and drain down and refill etc. but one cannot touch the cylinder itself unless one has the unvented ticket.
 
G

Goldspoon

what about two 2 port valves controlled from a stat on cylinder

ChrisR mentioned this (thks) and also mentioned them not being designed formains pressure. One has to go off if the other comes on so sounds a little more complicated. Will think about this one... thks

I wonder if there is something as simple as a manual lever/switch...
 
B

BigBurner

Okay, a three port valve sends water in one leg of the valve and can allow water left or right or left and right out of the other two legs.

Is there such a thing as this...

Imagine the T shape of the valve. Water enters from the top left. Water enters from the top right. The valve can choose which flow to allow down the vertical.

It looks like you need a normal blending valve. Check if the combi can take hot water into the cold inlet.

Hot into one port, cold into the other, blended user set temperature out. Two in, one out.

Do not block open vents etc.
 
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The easy solution is an isolation valve on the outlet of each system then one can be shut & one opened depending on the heat source used.if the combo can take preheated water then a blending valve is great.alpha use what they call a solar valve on their solar smart system I'm not sure if valve is available seperatly as this is the perfect solution. Another issue is water quality in the cylinder, during periods of not useing the wood burner the cylinder will be at lower temprrtures which is ideal breeding ground for legionella ect a better option would be a thermal store so there is minmal storage of hot water, it also gets around the invented issues
 
B

BigBurner

The easy solution is an isolation valve on the outlet of each system then one can be shut & one opened depending on the heat source used.

An auto blending valve is the way.

if the combo can take preheated water then a blending valve is great.alpha use what they call a solar valve on their solar smart system I'm not sure if valve is available seperatly as this is the perfect solution. Another issue is water quality in the cylinder, during periods of not useing the wood burner the cylinder will be at lower temprrtures which is ideal breeding ground for legionella ect a better option would be a thermal store so there is minmal storage of hot water, it also gets around the invented issues

That is more like it. :)
 
G

Goldspoon

The general idea is NOT to use the combi for HW except as a back up. All HW supplied by cylinder (heated by stove or immersion). So cylinder in regular use and kept piping hot. Combi is used for rads and is a back up for HW for times of heavy use.

I did mention in my original post that the combi is NOT one that can officially accept preheated water as then would put water straight in from cylinder with a pump and blending valve (cylinder vented).

I have another thread going about WHY one should not put preheated water into a combi not designed for it but am still non the wiser. I also rang three companies: Alpha, Atmos and one other to ask why (in other words what is it exactly about your boilers that means they accept preheated water) and in all cases nobody could answer the question. All took my tel no. (Fri am) and said someone techy would call - but nothing as yet.
 

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