Scheduled DHW Eco/Comfort mode: Remeha Calenta+Evhome+OT GW

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jgeo
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Scheduled DHW Eco/Comfort mode: Remeha Calenta+Evhome+OT GW

Post by jgeo »

I try to achieve a time-scheduled DHW mode switching between Eco- and Comfort mode, on a Remeha Calenta Ace 40c in combination with an Evhome (zoned thermostat) and possibly by using OpenTherm Gateway (OTGW https://www.nodo-shop.nl/en/opentherm-g ... teway.html) in combination with Home Assistant.

In Eco-mode, the Remeha heater only heats when hot water is requested, in Comfort mode, the heat-exchanger keeps being pre-heated to 45 degrees, and so the burner switches briefly on every 25 minutes. I'd like it to pre-heat in the morning and evening, but in Eco mode during the rest of the day.

The manual of the Remeha Calenta Ace 40c says I can set it to scheduled operation, but when I navigate to the clock-schedule it says "SEE RU". Which means that I should use the Remeha eTwist thermostat to achieve this, but I don't have one since I control my heating system with a Honeywell Evohome, since I have zoned floor-heating.

How can I probram this DHW mode?
1) Should it be possible to program it on the Remeha Calenta Ace 40c itself? If I would temporarily borrow an eTwist, can I program the heater for scheduled DHW mode switching, then replace the eTwist by the Evohome again, and have it running forever with the same schedule?
2) Does the eTwist normally execute the schedule, and would the Remeha Calenta Ace 40c just act as a slave? So is it only possible if an external device operates the DWH mode?
3) Can I set the mode through the OpenTherm interface?

In OpenTherm monitor (https://otgw.tclcode.com/otmonitor.html) there is an option (Configuration > Heater) for Comfort Setting (Comfort mode, Economy mode, Thermostat controlled). That seems to correspond to the setting on the boiler of
DP200=0 "klokprogramma" = scheduled (but setting the schedule does not work: SEE RU)
DP200=1 "handmatig" = manual (comfort mode)
DP200=2 "vorstbeveiliging" = freezing prevention (eco mode)
But unfortunately, that doesn't do anything with the behaviour of the system. I see a message in the Opentherm logging: HW=0 or HW=1 or HW=A, there is even a confirmation, but the Remeha keeps doing what it did according the the manual setting of the configuration menu on the boiler itself.

Remeha support is totally inadequate, and refer to my equipment installer, who tells me I shouldn't do those difficult things. So that's a dead end.

Opentherm Monitor: Economy Mode

Code: Select all

10:49:16.355276	T80000200	Read-Data 	Status (MsgID=0): 00000010 00000000
		   - DHW enable: enabled (1)
10:49:16.535341	R00000000	Read-Data 	Status (MsgID=0): 00000000 00000000
		   - DHW enable: disabled (0)
10:49:16.658800	BC0000000	Read-Ack  	Status (MsgID=0): 00000000 00000000
		   - DHW mode: not active (0)
10:49:16.781653	A40000200	Read-Ack  	Status (MsgID=0): 00000010 00000000
		   - DHW mode: not active (0)
Opentherm Monitor: Comfort Mode

Code: Select all

10:50:45.864392	T80000200	Read-Data 	Status (MsgID=0): 00000010 00000000
		   - DHW enable: enabled (1)
10:50:46.021366	B40000200	Read-Ack  	Status (MsgID=0): 00000010 00000000
		   - DHW mode: not active (0)
Opentherm Monitor: Thermostat controlled

Code: Select all

10:51:40.547413	T80000200	Read-Data 	Status (MsgID=0): 00000010 00000000
		   - DHW enable: enabled (1)
10:51:40.719299	B40000200	Read-Ack  	Status (MsgID=0): 00000010 00000000
		   - DHW mode: not active (0)
The only difference I see here is between switching the OpenTherm monitor mode to economy mode and the other modes:
Then it sends after the T80000200 Read-Data another R00000000 Read-Data.

According to http://otgw.tclcode.com/firmware.html, it should be possible to use the HW=... command to set the behaviour, but either it's not correctly passed to the boiler, or it's ignored. According to viewtopic.php?f=75&t=11896 I need to set the P4 but, but I have no clue how to do that.
hvxl
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Re: Scheduled DHW Eco/Comfort mode: Remeha Calenta+Evhome+OT GW

Post by hvxl »

The HW command does not result in changing a setting on the boiler. It just manipulates the DHWenable bit in the status message (MsgID 0). Your log excerpts show that the thermostat already had this bit set. This means that the water was probably already kept at temperature. So just quickly trying the different options will not show any changes. A change will only happen when the water cools down. With HW=1 it will be reheated, with HW=0 it won't. HW=A lets the thermostat control it. Your thermostat requested heating at the time you tested it, which is why it looks the same as HW=1.

According to [https://tools.remeha.nl/wp-content/uplo ... dout-3.pdf] P4 maps to DP200 on a Calenta Ace. And [https://www.remeha.nl/actueel/eco-mode- ... alenta-ace] says that DP200=1 equals comfort, and DP200=2 equals eco. If the story above doesn't seem to apply for you, that may be caused by the DP200 setting. Try changing it to 3 or 0 and test again.

Gateway firmware 6.2 introduced the new manual DHW push command (HW=P), which may be interesting for you. But if the boiler doesn't natively support DHW push, that feature falls back to manipulating the DHWenable bit. So it may only work if you can get the above working.

Firmware 6.2 also added the MW command that can change the DHW mode on boilers that support it. You can try if that works on the Calenta Ace. MW=3 should select comfort mode, and MW=5 frost protection.
Schelte
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