Smart heating controls with solid fuel stoves.
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12-04-2018 9:38am#1For those who have controlled trvs on their radiators, do you also have a solid fuel stove that can also heat the water for heating? I guess this may also apply to any secondary heat source aside from the boiler that is run by the smart controls.
I have found after 2 years of using the Evohome system, that it may be using more oil than it would if I didn't have it.
When the stove has the water good and hot, my setup allows the excess heat to 3 rads that are uncontrolled, but if they are not enough to dissapate the heat, the hot water tank in the attic overflows from the build up of pressure.
Unless the controlled rads are calling for heat, they obviously will not get any, but even if they are, they are mostly, possibly entirely, fed from the boiler.
So even if my stove has enough hot water to heat all the rads, that can get wasted, while the boiler burns oil to do the same job.
Won't be an issue for the summer as we rarely have the stove on then, but when we get to September and it comes back into use, I am thinking of removing some if not all the controlled trvs and sticking back the old manual controls. They will allow some heat through from the stove.
Unless I can find something that has enough intelligence to recognise the heat from the stove and gives that priority over the boiler, perhaps a script in Home Assistant (if I ever get it working - a different story altogether), I may remove the evohome system altogether and go with just one or two smart thermostats like Nest.0
Comments
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For those who have controlled trvs on their radiators, do you also have a solid fuel stove that can also heat the water for heating? I guess this may also apply to any secondary heat source aside from the boiler that is run by the smart controls.
I have found after 2 years of using the Evohome system, that it may be using more oil than it would if I didn't have it.
When the stove has the water good and hot, my setup allows the excess heat to 3 rads that are uncontrolled, but if they are not enough to dissapate the heat, the hot water tank in the attic overflows from the build up of pressure.
Unless the controlled rads are calling for heat, they obviously will not get any, but even if they are, they are mostly, possibly entirely, fed from the boiler.
So even if my stove has enough hot water to heat all the rads, that can get wasted, while the boiler burns oil to do the same job.
Won't be an issue for the summer as we rarely have the stove on then, but when we get to September and it comes back into use, I am thinking of removing some if not all the controlled trvs and sticking back the old manual controls. They will allow some heat through from the stove.
Unless I can find something that has enough intelligence to recognise the heat from the stove and gives that priority over the boiler, perhaps a script in Home Assistant (if I ever get it working - a different story altogether), I may remove the evohome system altogether and go with just one or two smart thermostats like Nest.
I need to get my head around this as well. We have nest controlling 3 zones (2 plus water), so they control the motorised valves which do the call for heat.
The issue I think is, that when we light the stove, we need to open one of the zone valves, but if we do this, it calls for heat to the oil burner. In fact, the only way we can now open the valves is by setting the thermostat temo on nest!!
Any ideas in how we should wire/rewire for this, in that the backbpiler should open a zone (valve) but not call for heat0 -
Have you seen this system: https://www.systemlink.ie/heat-genie.html - it might help. It does sound like you need a way to call on the stove first beford calling upon the boiler.
I've seen similar logic achieved with solar water heating controllers, whereby it tries to use solar heat source first, and if that isn't adaquete to maintain temp in the cylinder, it resorts to active backup like gas boiler or electric immersion.
Would another solution be to have a pipe stat on the stove supply (indicating stove heat available) wired through a relay. If it is active + the nest/evohome is calling for heat, it opens the zone valve. When the pipestat indicates no stove heat available, the relay is closed. And then if evohome/nest calls for heat, going through auxiliary on the relay, you could call in the boiler.
Workable? Do you by any chance have a rough piping diagram of what you have?0 -
@paulbok
i know you asked similar question here , any chance you can draw this on paper? i mean how this all fit together? what is the primary source of heat? or there isn't any primary source of heat but its matter of availability/demand i.e if solid fuel stove is on use its heat or if solid fuel stove isn't on start boiler if there is demand, how do you know if your stove got excess heat? is there any valve that is temperature controlled? those three rads have any trvs on them to control their temperature? again who make that choice that you have excess heat and 3 rods aren't enough to dissipate excess heat and it get to over flow in attic? sorry i only have gas boiler so its hard for me to picture this and i always had my boiler controlled by timer rather then manual thermostat and now with raspberry pi from web interface.For those who have controlled trvs on their radiators, do you also have a solid fuel stove that can also heat the water for heating? I guess this may also apply to any secondary heat source aside from the boiler that is run by the smart controls.
I have found after 2 years of using the Evohome system, that it may be using more oil than it would if I didn't have it.
When the stove has the water good and hot, my setup allows the excess heat to 3 rads that are uncontrolled, but if they are not enough to dissapate the heat, the hot water tank in the attic overflows from the build up of pressure.
Unless the controlled rads are calling for heat, they obviously will not get any, but even if they are, they are mostly, possibly entirely, fed from the boiler.
So even if my stove has enough hot water to heat all the rads, that can get wasted, while the boiler burns oil to do the same job.
Won't be an issue for the summer as we rarely have the stove on then, but when we get to September and it comes back into use, I am thinking of removing some if not all the controlled trvs and sticking back the old manual controls. They will allow some heat through from the stove.
Unless I can find something that has enough intelligence to recognise the heat from the stove and gives that priority over the boiler, perhaps a script in Home Assistant (if I ever get it working - a different story altogether), I may remove the evohome system altogether and go with just one or two smart thermostats like Nest.0 -
@paulbok
i know you asked similar question here , any chance you can draw this on paper? i mean how this all fit together? what is the primary source of heat? or there isn't any primary source of heat but its matter of availability/demand i.e if solid fuel stove is on use its heat or if solid fuel stove isn't on start boiler if there is demand, how do you know if your stove got excess heat? is there any valve that is temperature controlled? those three rads have any trvs on them to control their temperature? again who make that choice that you have excess heat and 3 rods aren't enough to dissipate excess heat and it get to over flow in attic? sorry i only have gas boiler so its hard for me to picture this and i always had my boiler controlled by timer rather then manual thermostat and now with raspberry pi from web interface.
I need to talk to my plumber to find out for sure how it is connected. There are 2 coils in the tank, one fed by the stove and one from the oil. After that I'm unsure how the tank feeds the manifold for the rads.
There is a stat on the stove supply that switches on a circulation pump to pump the heat to the uncontrolled rads, I think it also goes to controlled rads if they are calling for heat, but I believe the hot water from the oil would be the primary supply in this case. Another for my plumber to answer.0 -
Any update on this set up?
I'm in a similar situation.
Have oil boiler and also solid fuel stove.
2 motorized valves, one for upstairs and one for downstairs, a nest for each.
How can I set it up to work in sync with the stove?
Also have immersion for hot water when boiler and stove are off.
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Without the smart Thermostats (with zones valves open manually) can the boiler heat all of the radiators on it's own?
If so,
I'd imagine the thermostat for the solid fuel boiler could operate a relay to cut the oil boilers circuit preventing it from being called meaning the Nest thermostats operate the valves but can't call the oil boiler for heat. But I'd probably ask @deezell here https://www.boards.ie/discussion/2057758281/home-heating-automation/p141 about the correct way based on your plumbing.
I use Home Assistant with a smart switch, contactor and temperature sensor to control my immersion. I've solar hot water and have an automation set to run immersion if water hasn't met a certain temperature via boiler and / or solar on night rate electricity, only if the following day is forecast to be cloudy (and I can set level of cloud as an average percentage for the day).
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Because a stove can't be called on or off by a thermostat, it's integration into the system is independent of the smart stats. A stove generally should have a gravity feed to the HW cylinder on its own coil, or to a radiator, so that it can dissipate heat in the event of a power failure and no pumped circulation to the radiators. The stove should have a pipe stat on its hot flow out, to activate a circulation pump to the CH when its temperature rises past a threshold. It will heat the HW exclusively by gravity up to that point, then the radiators when it exceeds the threshold, about 56-60°. By using relays or a specific wiring box, often called a lex box, you can arrange the stove stat to operate it's circulation pump and open the valves to a zone, if the smart stats have not already opened them. The boiler call switched live (SL) combined from the zone valve relays can be also be obtained from the lex box if it is used as a wiring centre to receive the SL from the smart stats and send it to the valves. The lex also has a couple of extra relays, one of which can be used to interrupt the SL to the boiler when the stove stat activates and sends hot flow to the CH. When the stove flow reduces below the threshold, the boiler SL will be resumed from the smart stat combined inputs. If the smart stat temperatures are satisfied, no SL to the boiler and both CH zone valves are closed, the second relay can be used to open one of the zone valves to ensure stove hot flow can go to the rads. I've posted on this in the past in relation to stove/boiler combining. There are plumbing considerations as well, in how the flows are combined and mixed, and you can search through that linked thread to read about the techniques used. When its done right, it works very well.
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