Proton BASIC Community

Another random discussion

I'm looking at improving my heating system. I have a combi and while I may go for a heat pump in the future there are issues I have to sort first.

Since one of the really important systems to improving efficiency is weather compensation I want to retrofit it to my boiler. Weather compensation is adjusting the boiler flow temp based on the outside temperature. i.e. the colder it is outside the higher you set the boiler temp and vice versa.

It should just involve desoldering the temp control pot on the boiler PCB and replacing it with an D-A device. Or another way is to make a device to clip over the knob and use a servo to manually adjust the knob.

The rest is a temp probe outside and a screen to input the temp compensation curve info.

Just curious if you have any thoughts on it.

Cheers

Tim

Whilst your servo idea may be a bit clunky in some respects, it has the advantage that no modifications are required which is good from a warrantee and safety stance. The last thing you need is for some glitch or hardware failure to occur and the boiler just runs away to meltdown.

The more I look into this I see that most boilers can have the ability to add weather compensation however it seems that my boiler does not so the servo bodge looks like the best option to retro fit it on.

Tim

Hi Tim

My gas heating system is controlled by an 18F46K22, so no surprise there. I like the idea of weather compensation but I would hesitate before doing anything to the boiler electronics. If, God forbid, something went wrong then the first thing the accident guys would look at is any changes you had made.

But a servo turning the boiler knob sounds a good idea. I can feel a "Wallace and Gromit" design forming already....

Charlie

Why not just create a seperate monitoring unit, that tells you to change the settings? Then when changed, use its "OK" button to tell it they have been changed accordingly, so it knows for the next time?

That way, nothing is added to the boiler, because as Charlie stated, insurance companies will use "ANY" excuse not to pay a single penny for a repair or meintenance! But hopefully, it would never come to that.

Another scenario would be to switch the boiler on earlier in the morning if the outside temperature is low which is very safe to do.

It's okay to vary the flow temperature but beware of reducing efficiency, modern condensing boilers should not have the temperature of the water returning from the radiators exceed 55degC, otherwise efficiency is lost as the waste gases don't then condense.

https://www.trustedreviews.com/explainer/whats-best-temperature-condensing-boiler-set-3649148

QuoteFor the condensing boiler to operate at maximum efficiency, the secondary heat exchanger's surface needs to be equal to or below the dew point temperature of the fuel used. This is the temperature at which water droplets form. For natural gas boilers, the dew point is around 55C. In other words, the water in the return pipe needs to be 55C or lower or your boiler will not operate at maximum efficiency and potentially will not even condense.

Turning down the temperature on your boiler's central heating flow can help increase its efficiency. Boilers will have two dials: one to adjust hot water temperature (usually marked with a tap, or similar) and one to adjust central heating temperature (often symbolised with a radiator icon). Most modern boilers will have a mark on the screen that shows you the point at which condensing mode will be turned on. On my Ideal Logic+ C30, there's an 'E' icon on the central heating dial, which corresponds to 68C displayed on the screen. Generally speaking, a central heating temperature of 70C should work in most homes to get a boiler into condensing mode.

Of course the boiler setting is for the outgoing flow temperature so really you need to check the return flow temperature to ensure all is working efficiently.

John

Quote from: charliecoutas on Jan 31, 2025, 10:20 AMI like the idea of weather compensation but I would hesitate before doing anything to the boiler electronics. If, God forbid, something went wrong then the first thing the accident guys would look at is any changes you had made.

I would be more concerned about the engineer who is servicing it (particularly if it is a gas boiler) as any modification, particularly to the circuit could cause them to condemn it as unsafe as it is no longer functioning to it's original design.
Even though there is less chance of that happening with an external device mimicking a person turning the original flow knob instead doing it manually I would not be surprise it they still condemn it, because if there was subsequently an incident their head could be on the chopping block. Thus they would probably play safe and condemn any modification.

Quote from: TimB on Jan 31, 2025, 09:05 AMJust curious if you have any thoughts on it.

Hi Tim,

my boiler is outside the house in a small shed and hot water comes to the distribution unit through underground tubes.

My observation is that the biggest waste of efficiency is he fact that the circulation pump stops immediately after the burner stops, two things happen:

- the inlet tube stays full of hot water underground and between active periods more or less radiates the heat in the surrounding ground even-though that there's thick insulation.

- the boiler is still hot and radiates a lot of energy in the air while waiting for the thermostat to switch it on again.

So my thoughts are that if the circulation pump continues working for about 2-3 minutes after the burner stops, even-though the thermostat turned of the burner, this will bring most of that remnant energy in the house instead of dissipating in the ground and in the shed.

This is something I plan to change this summer, winter is not the time to modify the heating system

To improve efficiency I would think no dependencies but -
Do you have weather wherein a solar panel(s) can work ?
Also consider a heat exchange that makes drinking water from air perhaps.  Condensation takes place when the temperature between two sides exceeds a certain temperature.  Usually a cooling system is used to force condensation in ambient temperature.
One can put a peltier on a heated surface to power a fan to distribute heat in a space.  You can buy them too but expensive.  Unfortunately peltiers are very low efficiency.
Perhaps a heat exchange motor ?

Of course there are free energy technologies which have been suppressed for a long time.  Some may soon be revealed.

Thanks for all the great feedback

I already run my boiler at a low temp getting it to condense. I also like trastikata have issues with overrun of the pump. My boiler switches the pump off after 3 mins, I need to extend that to around 5 or more. That will be more invasive. But I want to stop it cycling. I'm will also try putting the boiler on the lowest setting and extending the on time to most of the daylight hours and have a high setback temp.

The servo on the front is the way to go. I will not de-solder any parts.

I have a nest thermostat originally I dumbed it down to just have fixed cycles now I'm going to go back to look at its smarts as it can look at the weather and bring the system on earlier to compensate.

 

Should have take a bus instead of a combi.  There's so many busses here to transport the striking masses they get burned 50 at a time...