Originally posted by orange
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Evohome - poor temperature regulation
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Honeywell thinks their software does not have critical mistakes in it, so they don't release updates. New units also have the same firmware. So far.
greyhound, you are correct. The radiator valve in zone B in your example should close much earlier. Letting it go 1.5 over setpoint is way too much.
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Originally posted by greyhound1234 View PostIgnoring arguments over how the TPI algorithms should behave, the behaviour of other zones is clearly not correct. Can anyone else replicate this?
e.g. Zone A and B both previously set to 17.0 and both holding 17.0. Zone A is then set to e.g. 20. Zone A will heat up. Zone B will heat up. Zone B will only stop heating up at 18.5 (1.5 degrees above it's setpoint, the zone valve closes off).
There is no way the Hr92 will call for heat unless your at set point (and been falling) or below) - it will then 'trickle' the water in to attempt to control the temp of the rad (at 17 degree) - are you saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? Or are you just looking at the room temp?
Is Zone A linked to Zone B? (next door? linking room? etc)getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own
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There are no firmware changes to the controller.
There are and have been firmware changes to the gateway - which provide enhancements, such as schedule editing etc - future enhancements are road mapped.getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own
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Originally posted by Rameses View Postgreyhound1234 - Firstly - when you say zone valve - do you mean Hr92 on the radiator? If so then how do you know this is open?
There is no way the Hr92 will call for heat unless your at set point (and been falling) or below) - it will then 'trickle' the water in to attempt to control the temp of the rad (at 17 degree) - are you saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? Or are you just looking at the room temp?
Is Zone A linked to Zone B? (next door? linking room? etc)
Yes HR92 valves.
I can tell when they are open, as the water flow is noisy in the valve (particularly when they are slightly open, it is clear to hear). They do close fully, but only at Tset+ 1.5 degrees.
"There is no way the Hr92 will call for heat unless your at set point (and been falling) or below)"
I don't think the HR92's make that decision. As is my understanding, they just report temperature to the controller. The controller then decides when to call for heat, and instructs the valve to open or close a bit.
Your statement also seems contradictory with that you said before, about a 1.5 degree overshoot being normal.
As stated previously, heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point. This is the undesirable behaviour we have been discussing.
"saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? "
No I mean it gets flowing hot water!
- No HR92 radiator valve closes down fully until a zone is 1.5 degrees higher than their set point. This is the same 1.5 degrees that the controller calls heat up to, probably not a coincidence.
- This means that when 1 zone calls for heat, other zones that are nicely at the set point and don't need heat will still receive new hot water to their radiators, until they 1.5 degrees over and their valves close.
Let me know if this is not clear.
If you are all using the same firmware, this should be easily reproducible.
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It should be easily reproducable indeed and it is! Except at Honeywell labs for some reason??? :S
Just to clarify: we're discussing 2 seperate issues:
1: the HR92 (or Evotouch), after calling for heat because of being below setpoint, keeps requesting heat from the boiler through the BDR91 for 1 minute every 10 minutes, even when the zone temperature is already way above setpoint and still rising.
As greyhound puts it is:heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point.Last edited by erik; 13 March 2015, 12:21 PM.
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Originally posted by greyhound1234 View PostHi
Yes HR92 valves.
I can tell when they are open, as the water flow is noisy in the valve (particularly when they are slightly open, it is clear to hear). They do close fully, but only at Tset+ 1.5 degrees.
"There is no way the Hr92 will call for heat unless your at set point (and been falling) or below)"
I don't think the HR92's make that decision. As is my understanding, they just report temperature to the controller. The controller then decides when to call for heat, and instructs the valve to open or close a bit.
Your statement also seems contradictory with that you said before, about a 1.5 degree overshoot being normal.
As stated previously, heat is not initially called in a zone until it is at the set point and falling, but once called, it continues to be pulsed up to Tset + 1.5 degrees. i.e. heat calls are made continuously and repeatedly until 1.5 degrees over set point. This is the undesirable behaviour we have been discussing.
"saying that the radiator (zone b) is on and warm (and I mean was not getting hot water)? "
No I mean it gets flowing hot water!
- No HR92 radiator valve closes down fully until a zone is 1.5 degrees higher than their set point. This is the same 1.5 degrees that the controller calls heat up to, probably not a coincidence.
- This means that when 1 zone calls for heat, other zones that are nicely at the set point and don't need heat will still receive new hot water to their radiators, until they 1.5 degrees over and their valves close.
Let me know if this is not clear.
If you are all using the same firmware, this should be easily reproducible.getconnected.honeywell.com | I work for Honeywell. Any posts I make are purely to help if I can. Any personal views expressed are my own
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Originally posted by Rameses View PostIs Zone A linked to Zone B? (next door? linking room? etc)
It is not heat transfer I am talking about. I am not talking about just the temperature increasing. I am saying that since radiator valves do not close until 1.5 degrees past the set point, other zones radiators will naturally run hot when any zone calls for heat.
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Or to put in really simply.
Zone A at the right temperature, radiator cold. Zone B at the right temperature, radiator cold.
Zone A is ramped up in temperature. Zone A calls for heat. Zone B does not. But both radiators get hot. Zone A runs until Zone A set point + 1.5 degrees. Zone B runs until Zone B set point + 1.5 degrees.
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Originally posted by greyhound1234 View PostOr to put in really simply.
Zone A at the right temperature, radiator cold. Zone B at the right temperature, radiator cold.
Zone A is ramped up in temperature. Zone A calls for heat. Zone B does not. But both radiators get hot. Zone A runs until Zone A set point + 1.5 degrees. Zone B runs until Zone B set point + 1.5 degrees.
what TRV bodies do you have?
Are you sure that when the HR92 is closed that there is no flow through the radiator?I work for Resideo, posts are personal and my own views.
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Originally posted by top brake View Postsounds very much like the TRV are not physically closing fully...
what TRV bodies do you have?
Are you sure that when the HR92 is closed that there is no flow through the radiator?
They definitely do close fully, but only when the Evohome tells the HR92 to close them fully!
I can get zones to heat completely independently and the other radiator stay cold - providing the other zone is more than 1.5 degrees above it's set point. If not, then the valve will be at least partially open.
This is the same 1.5 degree offset that the Evohome controller is using in heat demand also. This can't be a coincidence. If I was to take a punt, I would say there will be a hard coded number in the algorithm, it should read '0.5' but someone made a typo and did 1.5.
Anyway hopefully the symptoms are clear now.
To summarise.
Zone valves are not instructed to fully close until temperature is 1.5 degrees over the set point. This leads to overshoots on all zones when heat demand is called.
Zones will first call for heat when they are at or less than the set point. But once called, zone will continue to call for heat all the way up to 1.5 degrees over the set point.
If this '1.5' was '0.5', this would be acceptable/expected.
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Originally posted by top brake View Postsounds very much like the TRV are not physically closing fully...
If Honeywell would take 15 minutes to actually test the behavior of a HR92, you would see exactly the same thing. Or are you saying this is not normal behavior, top brake? Do your tests show other results?Last edited by erik; 13 March 2015, 01:49 PM.
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Originally posted by greyhound1234 View PostThey are Honeywell VT117 bodies.
They definitely do close fully, but only when the Evohome tells the HR92 to close them fully!
I can get zones to heat completely independently and the other radiator stay cold - providing the other zone is more than 1.5 degrees above it's set point. If not, then the valve will be at least partially open.
This is the same 1.5 degree offset that the Evohome controller is using in heat demand also. This can't be a coincidence. If I was to take a punt, I would say there will be a hard coded number in the algorithm, it should read '0.5' but someone made a typo and did 1.5.
Anyway hopefully the symptoms are clear now.
To summarise.
Zone valves are not instructed to fully close until temperature is 1.5 degrees over the set point. This leads to overshoots on all zones when heat demand is called.
Zones will first call for heat when they are at or less than the set point. But once called, zone will continue to call for heat all the way up to 1.5 degrees over the set point.
If this '1.5' was '0.5', this would be acceptable/expected.
gone through CYCL optimisation?
if you short press the button on HR92 does it display zone B name?
did you encounter any issues when binding?I work for Resideo, posts are personal and my own views.
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Is there a point after 1000 questions where Honeywell will finally say: ok, seems like the system has mistakes in it. We will look at it and try to fix it.
Or will Honeywell keep believing the system is perfect and that every problem must be a user mistake, no matter what?
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