DHW control of Baxi boiler with storage tank
Posted: Mon May 15, 2017 7:23 am
Hi all!
I'm new here and have just overcome the complications of a full renovation of the heating system of my house. My choice was a Baxi Duo-Tec Compact+ boiler due to it's size and support for OT. I'd like to have some control over it's behavior but at least to monitor what it does and how, that's why I also purchased an OT gateway right after the heating system was deployed. I have not bought a Baxi thermostat yet, though, since I could not get it's user's manual to be sure about what it supports in terms of programming (and it's relatively expensive due to the lack of information I could get about it's capabilities). It's BAXI 7104336 or it's wireless counterpart BAXI 7105432. I think these support weekly CH and DHW programs, but others reported that there are too few daily CH setpoints to be convenient for them. Anyway, prior to investing in a room thermostat I wanted to see whether I could control on my own using the wireless room sensors all over the house and create DHW based on our measured needs.
So I started to experiment with the GW these days, attached the gateway to the boiler and had immediate success: they started the conversation and after some time I was able to start/stop central heating and set the control setpoint. After some investigations I was also able to control the DHW setpoint of the boiler by issuing SW serial commands from otmonitor, and discovered the HW=1 command as well (comfort mode on the interface), which enabled DHW. Added alternative commands 3 and 26 for slave configurations and DHW temperature respectively, so that the monitor get more info about the slave, and afterwards I saw the DHW properties and the measured DHW temperature reported to the monitor periodically. And I got stuck: even if I enable DHW and the measured DHW temperature goes below the setpoint (ie. below 37 degrees currently), nothing happens. When the gateway is not attached, the boiler on it's own started to heat the DHW tank, but with the gateway nothing happens. I think I miss something at this point: I can't figure out how to instruct the boiler to switch the valve (do I need to instruct it at all?) and start heating the DHW. For CH it was easy, I only issue the CS=x command and it sets the CH flag automatically, then the boiler starts to heat, nothing else is needed. I can switch it off with CS=0 or CH=0, both are OK. But nothing happens for DHW, regardless of what is set by SW command, what's the measured DHW temp and whether I issue HW=1 or not.
Here's a snippet from the logs, maybe it helps someone to figure it out even faster:
Thanks in advance for any help!
I'm new here and have just overcome the complications of a full renovation of the heating system of my house. My choice was a Baxi Duo-Tec Compact+ boiler due to it's size and support for OT. I'd like to have some control over it's behavior but at least to monitor what it does and how, that's why I also purchased an OT gateway right after the heating system was deployed. I have not bought a Baxi thermostat yet, though, since I could not get it's user's manual to be sure about what it supports in terms of programming (and it's relatively expensive due to the lack of information I could get about it's capabilities). It's BAXI 7104336 or it's wireless counterpart BAXI 7105432. I think these support weekly CH and DHW programs, but others reported that there are too few daily CH setpoints to be convenient for them. Anyway, prior to investing in a room thermostat I wanted to see whether I could control on my own using the wireless room sensors all over the house and create DHW based on our measured needs.
So I started to experiment with the GW these days, attached the gateway to the boiler and had immediate success: they started the conversation and after some time I was able to start/stop central heating and set the control setpoint. After some investigations I was also able to control the DHW setpoint of the boiler by issuing SW serial commands from otmonitor, and discovered the HW=1 command as well (comfort mode on the interface), which enabled DHW. Added alternative commands 3 and 26 for slave configurations and DHW temperature respectively, so that the monitor get more info about the slave, and afterwards I saw the DHW properties and the measured DHW temperature reported to the monitor periodically. And I got stuck: even if I enable DHW and the measured DHW temperature goes below the setpoint (ie. below 37 degrees currently), nothing happens. When the gateway is not attached, the boiler on it's own started to heat the DHW tank, but with the gateway nothing happens. I think I miss something at this point: I can't figure out how to instruct the boiler to switch the valve (do I need to instruct it at all?) and start heating the DHW. For CH it was easy, I only issue the CS=x command and it sets the CH flag automatically, then the boiler starts to heat, nothing else is needed. I can switch it off with CS=0 or CH=0, both are OK. But nothing happens for DHW, regardless of what is set by SW command, what's the measured DHW temp and whether I issue HW=1 or not.
Here's a snippet from the logs, maybe it helps someone to figure it out even faster:
Code: Select all
18:12:50.379235 R80380000 Read-Data DHW setpoint: 0.00
18:12:50.500077 BC0382500 Read-Ack DHW setpoint: 37.00
18:12:51.439296 R00390000 Read-Data Max CH water setpoint: 0.00
18:12:51.556307 BC0395555 Read-Ack Max CH water setpoint: 85.33
18:12:52.499241 R801A0000 Read-Data DHW temperature: 0.00
18:12:52.614386 B401A2433 Read-Ack DHW temperature: 36.20
18:12:53.556307 R00120000 Read-Data CH water pressure: 0.00
18:12:53.674230 B40120133 Read-Ack CH water pressure: 1.20
18:12:54.292459 Command: AA=3
18:12:54.310325 AA: 3
18:12:54.617057 R80000200 Read-Data Status: 00000010 00000000
- CH enable: disabled (0)
- DHW enable: enabled (1)
- Cooling enable: disabled (0)
- OTC active: not active (0)
- CH2 enable: disabled (0)
- Summer/winter mode: winter (0)
- DHW blocking: unblocked (0)
18:12:54.733293 BC0000000 Read-Ack Status: 00000000 00000000
- Fault indication: no fault (0)
- CH mode: not active (0)
- DHW mode: not active (0)
- Flame status: flame off (0)
- Cooling status: not active (0)
- CH2 mode: not active (0)
- Diagnostic indication: no diagnostics (0)
- Electricity production: not active (0)
18:12:55.675299 R80190000 Read-Data Boiler water temperature: 0.00
18:12:55.792588 B40192299 Read-Ack Boiler water temperature: 34.60
18:12:56.734301 R10014100 Write-Data Control setpoint: 65.00
18:12:56.874376 BD0014100 Write-Ack Control setpoint: 65.00
18:12:57.793291 R00030000 Read-Data Slave configuration: 00000000 0
18:12:57.912067 B40031F1B Read-Ack Slave configuration: 00011111 27
- DHW: present (1)
- Control type: on/off (1)
- Cooling: supported (1)
- DHW: storage tank (1)
- Master pump control: not allowed (1)
- CH2: not present (0)
- Remote water filling: available/unknown (0)
- Heat/cool mode control: heat (0)
18:12:59.116930 R00110000 Read-Data Relative modulation level: 0.00
18:12:59.120128 BC0110000 Read-Ack Relative modulation level: 0.00
18:12:59.937003 R001B0000 Read-Data Outside temperature: 0.00
18:13:00.371953 BC01B1400 Read-Ack Outside temperature: 20.00
18:13:00.969371 R801C0000 Read-Data Return water temperature: 0.00
18:13:01.086373 B401C1B00 Read-Ack Return water temperature: 27.00
18:13:02.028290 R900E6400 Write-Data Maximum relative modulation level: 100.00
18:13:02.145350 B500E6400 Write-Ack Maximum relative modulation level: 100.00
18:13:03.087286 R801A0000 Read-Data DHW temperature: 0.00
18:13:03.223381 B401A2433 Read-Ack DHW temperature: 36.20