New oil boiler with load compensation

[mbguid]

I am planning to replace my old boiler with a new oil boiler. Gar is not an option where I live.

I want to maximise the efficiency of the system controls. I already have three heating zones (living areas, bedrooms and bathrooms) and would like a controller which could manage these zones, DHW and provide load compensation.

My thinking is that it must be more efficient to have all the zones managed by a single controller as that could control boiler firing more efficiently than the present independent programmable thermostats and load compensation should keep the boiler operating in condensing mode more often.

Apart from the (expensive) Honeywell hometronic and Smile systems, I have yet to find a controller which can do this. Any suggestions? I'm thinking of using a Grant boiler but again am open to suggestions. Veissman sound good but don't seem to sell oil boilers in the UK.

Thanks for any ideas.

Mike.

 

[Rhondo]

Grant are good boilers and I see they now supply a boiler energy management system. The controller looks like a rebadged Kanmor which I think are pretty good controllers.

A reasonable control like this will set you back about £1000 when comissioned.
There's better available if you wanted to spend upwards of £1800.

There's a host of elaborate room stats available now but not sure if they provide load compensation.
Weather compensation with an indoor sensor is better I believe if my googling exploits and internet scouring are to be believed.
I get my sf boiler loading valves here....
http://www.termomix.co.uk/automix30.html

They do a few compensators also but not sure if they any good but they look the biz and that always impresses the customers.
I'm just a cowboy.

 

[mbguid]

Thanks for the vote of confidence in Grant. What I really want in a controller is for one system to do everything, so it manages the three zones AND does the load compensation. I think this has to be better than separate systems.

There does seem to be a lot of confusion about load vs weather compensation, which has been discussed at length in another topic on this forum. I agree with the view that you don't actually need the external temperature measurement if you know and track the internal temperature since what's really important is the actual heat loss and you can work that out if you know how the internal temperature changes with boiler input.

My existing thermostats already do optimised start and operate PID control algorithms. They were state of the art 10 years ago and most of the UK market is yet to catch up, but I'd like to try to do better.

Mike.

 

[oilhead]

Load compensation on an oil boiler? I don't think so.

 

[Rhondo]

Load compensation on an oil boiler? I don't think so.

Sorry mate what is load compensation? I'm not big into controls.
Is it better or worse than weather compensation do you think?

 

[Boilerman2]

To achieve Weather compensation on an oil boiler the system would have to incorporate a Motorised mixing valve as oil burners fire at a fixed rate only, by mixing return water with the outgoing flow, the water temp at the rads is reduced the boiler will cycle on it's own thermostat (about 70'C)

I personally would fit Honeywell CM Series Prog Room Stats in each of the zones as these operate very efficiently and can be set up with oil fired boilers in mind

 

[mbguid]

Thanks for the inputs. I do understand that I would need a mixing valve. Going back about 15 years Yorkpark used to do this as standard but I think they went bust; hopefully no connection...

The Honeywell CM programmable thermostats are no more advanced than the ones I have had for the past 15 years.

As I said at the beginning, I would like to find a controller which can handle the three heating zones and the mixing valve together as an integrated system. This must result in better overall control and more efficient operation. One of the issues with using separate thermostats is that they call for heat independently and so the boiler will be cycling more frequently than if both thermostats were synchronised.

Mike.

 

[oilhead]

With compensation on the main circuit, you will still need individual zone control with a valve for each zone, as it is probable that you will have a mixture of satisfied and demanding zones.
Does the size of the system warrant such sophistication and complexity?

 

[htgeng]

My thinking is that it must be more efficient to have all the zones managed by a single controller as that could control boiler firing more efficiently than the present independent programmable thermostats and load compensation should keep the boiler operating in condensing mode more often.

Mike.

The Danfoss BEM 5000 would do what you want, but think it has been discontinued by them. You could always call them to ask? I seem to recall there being a setting on it with regard to oil boilers, but does your oil boiler require a minimum return temp if its a condensing boiler??

 

[mbguid]

With compensation on the main circuit, you will still need individual zone control with a valve for each zone, as it is probable that you will have a mixture of satisfied and demanding zones.
Does the size of the system warrant such sophistication and complexity?

Obviously I already have the plumbing configured with the zone valves to split the system into the three zones (as I did this 15 years ago) and clearly I will still need three temperature sensors but one controller could read all three and control the three zone valves, mixing valve and boiler with several advantages over the simpler system you are advocating, which I already have. I'll make the judgement of whether I want to implement this sort of controller when / if I find one. Given that the plumbing is mainly in place and I have to change the boiler anyway the cost of the controller is the main factor for me. £3k for the Hometronic system would not be worth it but £500 might be.

I get the impression that this is pretty standard in Germany but we seem to be stuck in the plumbing dark ages in the UK.

Mike.