Advantages of Direct Heated cylinder

[LeakyNick]

Hi

I'm looking at a thermal store which gives mains pressure hot water. The store will be heated by a solid fuel burner and a gas-boiler. I could have two coils put in the store (one for gas, one for stove) but I could also do-away with one coil and (say) have the stove directly connected to the store's fluid. Are there any advantages/disadvantages of going direct with one of the heat sources, instead of having two coils?

Thanks

Leaky

 

[ecowarm]

Hi

I'm looking at a thermal store which gives mains pressure hot water. The store will be heated by a solid fuel burner and a gas-boiler. I could have two coils put in the store (one for gas, one for stove) but I could also do-away with one coil and (say) have the stove directly connected to the store's fluid. Are there any advantages/disadvantages of going direct with one of the heat sources, instead of having two coils?

Thanks

Leaky

I would have them both direct, If the gas boiler is a condensing boiler it will be more efficient as it will have a lower return temperature which is better.

Speak to the thermal store manufacturer for advise, I use Newark Copper Cylinders and are very helpful. DPS are also very helpful but pricey!

Eco

 

[LeakyNick]

Thanks Eco. I will speak to Newark but if I go direct heating, are there any disadvantages in having the return (say) 12" from the bottom of the tank? Basically, I'm doing a solar install and the woodburner isn't powerful enough to heat the entire tank so I'm wondering about convection currents being a problem if the return isn't at the bottom of the tank.

Leaku

 

[ecowarm]

Thanks Eco. I will speak to Newark but if I go direct heating, are there any disadvantages in having the return (say) 12" from the bottom of the tank? Basically, I'm doing a solar install and the woodburner isn't powerful enough to heat the entire tank so I'm wondering about convection currents being a problem if the return isn't at the bottom of the tank.

Leaku

Newark will build you one to that spec. but normally for solar the bottom of the cylinder is solely for the solar anyway and everything else is taken above that.
The convection currents are not a problem from any input or output on the cylinder.

Eco

 

[LeakyNick]

Cheers. Thanks for the info.

Leaky

Another question that has arisen.... as I'm changing the old vented cylinder for a vented thermal store, should the old cold-feed cistern be changed for a smaller F&E cistern, or is it OK to leave-as-is?

Leaky

 

[ecowarm]

Cheers. Thanks for the info.

Leaky

Another question that has arisen.... as I'm changing the old vented cylinder for a vented thermal store, should the old cold-feed cistern be changed for a smaller F&E cistern, or is it OK to leave-as-is?

Leaky

You get quite a lot of expansion with a thermal store because of the extra water content in the system, if the old cold feed cistern is in good clean condition it would be ok to use this

Eco

 

[LeakyNick]

Thanks Eco. Would the system run OK without some sort of corrosion inhibitor in it, or should some be added?

Leaky

 

[ecowarm]

Thanks Eco. Would the system run OK without some sort of corrosion inhibitor in it, or should some be added?

Leaky

No you need inhibitor and for the increased water volume you need to add more than a standard system

 

[aim plumbing]

mcdonald engineers have a thermflow cylinder which can be ordered to you spec, the solid fuel can heat the cylinder and coils can be added for gas/oil/solar or all three. it has mains pressure hot water heated by an efficient coil. look at http://www.mcdonald-engineers.com/images/literature/Therm Flow Lft.pdf

 

[ecowarm]

I've used both but I prefer newark and are cheaper, more helpful and to the same spec

 

[LeakyNick]

Standard central-heating inhibitor ok?

Leaky

 

[mrlennie]

Sorry can I butt in and ask how is it vented yet provides hot at mains pressure?

 

[stevetheplumber]

Sorry can I butt in and ask how is it vented yet provides hot at mains pressure?

the heating side is vented and the main runs though a coil at the top
do solid fuel boilers need metal f and e tanks ?

 

[mrlennie]

Ah i c so like a combi with a store

 

[LeakyNick]

the heating side is vented and the main runs though a coil at the top
do solid fuel boilers need metal f and e tanks ?

I reckon they do as if the system vents-over too much, then it'll melt the cistern. Very dangerous.

Leaky

 

[ecowarm]

Standard central-heating inhibitor ok?

Leaky

Yes..........