Ferroli Aquasol with OpenTherm

This Forum is about the Opentherm gateway (OTG) from Schelte

Moderator: hvxl

Ferroli Aquasol with OpenTherm

Postby BarthoD » Sun Apr 04, 2021 8:28 pm

Opentherm Gateway with Ferroli Aquasol Sun Boiler system - protocol and connetion issues.

Question: who has any info about the Ferroli Aquasol(4) and a connection to OTGW ?

I have an Ferroli Aquasol 4 with a sunpanel PV-size from HR-Solar. Avery good combination.
I want to read the status of the sunboiler system using the OTGW; using just a monitor function. I have no thermostat connected.

Ferroli documentation:
The system is capable of "speaking" OT (which seems to be standard at AgpoFerroli.
When connected to th AgpoTherm PLus is should be able to show OT 25 (Boiler water temp), 27 (Outside air temp) , 29 (Solar Storage Temp).

OTGW: I use the NODO OTGW with Wifi and I have updated all SW to 5.1 (the complete SW stack as advised by otgw.tclcode.com).
All OTGW commands seem to work but I get 0, nothing from the boiler.
I have added (AA command) the three messages 25,27,29.

When in Monitor mode nothing happens, in GW mode I see the 1-second request on my oscilloscope coming; but no response whatsoever from the boiler.
The power on the boiler output is 17,1V (=); the GW message is about 1,2V.
Test5 response on Voltage levels is Themostat (but not connected) 2.95 Boiler=0, Reference voltage 1.21. Test 6 : nothing, nada, no esponse.
Starting Member
Starting Member
Posts: 2
Joined: March 2021

Re: Ferroli Aquasol with OpenTherm

Postby BarthoD » Fri Apr 09, 2021 8:39 pm

Today I learned that this boiler system is originally developed by ZEN (Zonne Energie Nederland - went broke 2014) and is taken over by Itho Daalderop. They are the builder of the equipment and electronics. On none of the sites of the companier there is any information, other van the mentioning of the boiler being able to provide a few temperaures and more via OpenTherm.

A comment that was made: the SUNboiler expects to be connected to an after heating (real) boiler with Opentherm. The path should be:
THERMOSTAT <opentherm> SUN Boiler <opentherm> BOILER (Naverwarmer)
The sugestion was made that the requests is coming from the T, picked up by the SUN boiler, who passes the message to the boiler, who returns an ACK + info, picked up again by the SUN boiler and passed back to the Thermostat.

In stead of the above, I have just connected the OTGW as a monitor to the SUNboiler. There is NO connected post-heating boiler (and there will not be).

My config is just:
(monitor) OTGW <opentherm> SunBoiler

The documentation suggestes that ANY after-heating boiler can do the job and can be connected with open-therm.
Question: what is the normal response from a boiler/heater back to a thermostat?

Because I use the OTGW just as a monitor I can use the 2nd connection to play the role as after boiler and send the right messages back (fake) ? What is the procedure and how can I close the loop?

The config will then be: :
OTWG T-connector <opentherm > sunboiler- B-channel
OTGW B-connecor <opentherm> sunboiler > T-channel

Any suggestions? Any experience?
Starting Member
Starting Member
Posts: 2
Joined: March 2021

Re: Ferroli Aquasol with OpenTherm

Postby hvxl » Sat Apr 10, 2021 10:32 pm

It sounds like the SUN boiler is acting as a gateway. Probably it passes requests on to the post-heating boiler and fills in some of its own information. I can see how that is possible for MsgID 27, and 29. Most regular boilers will not provide this information. But MsgID 25 is normally reported by the boiler. If the SUN boiler changes that information, it could affect the ability of the thermostat to control the boiler.

I was going to suggest that you connect both interfaces of the OTGW to the two interfaces of the SUN boiler. But in that case you can't use the normal firmware on the OTGW. You would need to flash the interface firmware and create some external program to generate the opentherm messages. The program would send a request message to the OTGW. That sends it to the SUN boiler, which then sends some request to the OTGW. Upon receiving that request, the program creates a response, which then travels back along the path through the SUN boiler to the OTGW.By varying the requests, you can reverse-engineer what the SUN boiler does. But the first step is to see if the SUN boiler actually sends out a message on its B-channel when it receives something on its T-channel.
Senior Member
Senior Member
Posts: 1490
Joined: June 2010

Return to Opentherm Gateway Forum

Who is online

Users browsing this forum: No registered users and 1 guest