Advice needed on heat exchangers for log boiler

[PinkyPerky]

Hello
I would welcome advice on heat exchangers for a log boiler.
First a description on my system:
Existing system:
This is a 115000BTU = 33kW sealed system pressure-jet oil boiler. This has a very low water content as the radiators are either fan convectors, Finrads or bathroom towel rails.
The system has two pumps, one for heating (two zones - downstairs+bathroom, upstairs+bathroom) and the other for domestic hot water.
A Horstmann Channel Plus programmer having 2 heating circuits and DHW, separately controls the valves, using their SPT relays to control the boiler and pumps. The oil boiler will be moved to the boiler house next spring when I hope to commission the whole system.
Additional New System:
I have built a boiler house for an Orlan 40kW log boiler with two 1000 litre accumulators and these and the flue are installed but not plumbed yet. I have a Laddomat and expansion tanks. Connection to the house will be by Openor quadro but I haven’t dug the trench yet
I have a 6x20 tube solar array which will heat one accumulator through its coil and be diverted to that in the second accumulator in a good summer, though I could split into two arrays and heat each accumulator. I still have to devise controls to keep stratification in the accumulators.

I want to keep the two systems separate. I did consider a LLH but it wouldn’t allow this.
I instead propose connecting the two accumulators to one or two multiplate heat exchangers for heating and connecting the accumulator with solar input to a third multiplate heat exchangers for the dhw. These would be in the boiler house with the existing system plumbed in afterwards, with motorised valves to keep the systems separate as only one system will be used at a time. I can then use one pair of Uponor pipes for heating and the other for dhw. This would allow me to use the existing pumps and expansion vessel inside the house and leave the house system unchanged.
I am not familiar with plate type heat exchangers and wonder if anyone could recommend suitable ones that I could use with my system.
I welcome advice!
Thanks
Vic

 

[lame plumber]

why would you go for plate heat exes when you have the ideal set up for thermal stores and blending valves off the stores coil for hw and direct water to heating?

 

[PinkyPerky]

Hi
Because I want to keep the systems separate

 

[Ermintrude]

Sounds v. Complicated? Belt braces and bit of string?

 

[Howsie]

Sounds like a lot of expense for 'just' 33k.

 

[PinkyPerky]

Sounds like a lot of expense for 'just' 33k.

Not sure I know what you mean?

 

[SimonG]

LP hit the nail on the head, why over complicate?

 

[lame plumber]

sounds like a bit of knowledge being dangerous, surely to be efficient you need to keep the system as one.

 

[Howsie]

Not sure I know what you mean?

All for 33kw.

 

[PinkyPerky]

Thanks for your comments but don't agree. Why should I go from a system with very low water content to one which has 2000+ litres when I may not always use the log-boiler?
By moving the motorised valves to the accumulator side of the heat exchangers I can use just one heat exchanger for heating and one for dhw. How is that over complicated?

 

[Ermintrude]

High volume systems have a grater ability to sore low grade heat. Small volume has virtually no thermal inertia and plate to plate require 10c drop between fluids as a minimum or u end up with 20000 plates with a surface area of 4 miles sq costing a zillion dollars even with counter current circulation. Think some smart systems have a thermal gradient through the store, so that they can be partially or fully used. You could should you wish have stores linked in parallel with conditional controls, once number 1 is up to temp bring in number two which normally is set 25c lower as so it can use residual energy from tank one?

 

[Dotty]

What do you do for a living Vic?

 

[Ermintrude]

What do you do for a living Vic?

My guess is electrical design engineer or fitter on a rig? Sounds like knows abit about mechanical ? Maybe process engineer ?

 

[Howsie]

I still haven't finished my bridge!

 

[PinkyPerky]

You could should you wish have stores linked in parallel with conditional controls, once number 1 is up to temp bring in number two which normally is set 25c lower as so it can use residual energy from tank one?

That is what I have.
I take your point about high volume systems but there is no way I am going to heat 2000 litres by oil! My low volume system heats up near instantaneously and there is efficient

 

[Ermintrude]

The free heat does it? Solar and when no or insufficient use oil? ACV cylinders look like the best ones? Perhaps u could have cylinder 1 at say 210 litres and then when no solar or free energy available you only heat that one, suspect you could do this by means of a pipe stat on solar unit as when hot, open up valves to cylinders two three and so on? Are you on a cesspit?

 

[mutley racers]

The free heat does it? Solar and when no or insufficient use oil? ACV cylinders look like the best ones? Perhaps u could have cylinder 1 at say 210 litres and then when no solar or free energy available you only heat that one, suspect you could do this by means of a pipe stat on solar unit as when hot, open up valves to cylinders two three and so on? Are you on a cesspit?

So it is you, zeebeedy. Cheeky monkey. To be honest, I thought you were a bit more knowledgeable than you

 

[Ermintrude]

So it is you, zeebeedy. Cheeky monkey. To be honest, I thought you were a bit more knowledgeable than you

Ay ? What's that mean?

 

[Deleted member 7121]

I have seen this done but not the best , think the heat exchanger was made by uk exchangers ltd if that the way you want to go