viessman/opentherm/evohome/pandora poor DHW

[Twenty Four]

Gratis verzonden too!

How do you read what it will do in English?

I wonder if Dan can afford one?


Simple question, when told its heating hot water, does the IG run/accept/expect a lower diff?

Tony

You could always change the page at the top to read in English.

 

[Twenty Four]

Failing that.

An assembled and tested USB OpenTherm gateway, ready to go! Everything you need is included.

The OpenTherm Gateway is an opensource project to monitor and control your OpenTherm compatible boiler, created by Schelte Bron. More in-depth information can be found on his website and there also is a dedicated forum on domoticaforum.eu.

PIC programming
This product comes with a pre-programmed PIC with diagnostic firmware. To use this product as an opentherm gateway you have to load the correct firmware. You can update the firmware yourself using the tools you can find on: http://tclcode.com/opentherm/download.html

Features

• Forward OpenTherm messages between the thermostat and the boiler
• Report about the messages on the serial interface
• Change the thermostat setpoint
• Set the clock of the thermostat
• Send the outside temperature to the thermostat
• Smart power support
• Support Opentherm and on/off thermostat, or even no thermostat at all
• Read an outside temperature sensor
• Control the domestic hot water option of the boiler
• Obtain additional information from the boiler
• Firmware updates through the serial interface

What is included?

• Assembled OpenTherm Gateway board
• Enclosure
• AC-cable with EU plug
• USB-TTL cable

 

[Agile]

That's easier to read.

Seems to be just what Dan needs!

As it also accommodates WC then its just what Alec needs too.

It also seems to be a cheaper alternative to a Vaillant controller. Even if it does not come in a grey box to fit the front of the boiler.

 

[Dan Robinson]

does the IG run/accept/expect a lower diff?

Think I need Google translate.

It also seems to be a cheaper alternative to a Vaillant controller.

Probably not.

 

[D_Hailsham]

These sites will tell you everything you need to know:

Opentherm Gateway Information

Opentherm Gateway Forum

 

[simond]

I love the watched pot never boils analogy, Dan. It is so on the money for Evohome. Poetry.

 

[Dan Robinson]

I love the watched pot never boils analogy, Dan. It is so on the money for Evohome. Poetry.

I hate that squeaky bum moment when you first test everything and it doesn't shut off the BDR when you think it will

 

[sandyman44]

just wanted to update and thank all for their help. 3 weeks ago my installers came back (for free). honeywell opentherm controller is now fitted, pump control is driven from boiler not from evo bdr, viessman DHW demand box is now fitted (wired to activate when DHW calls). System is now a logical W-plan (master zone valve on CH, shuts when DHW zone valve opens). guess what, the damn thing works properly now! boiler gets to 75-80 in a very small number of minutes when the DHW is calling (I get the "tap" symbol on the boiler) , it stays at that temp until we are done, and the cylinder reheats in no time at all.

I only had one cold week with opentherm, however during that time I did notice an change in behaviour that some might find of interest. As I have 5 months of pre (BDR on/off CH) and 1 week of post (opentherm) behaviour experience with the same rad configuration. At the mid-late evening stage when not much heat is needed (just 1 or 2 rooms asking for top-ups) the BDR method would fire the boiler up to 50 odd and run the pump, for 10 mins or so, then shut down both boiler and pump. noticeable boost to the room temp during those 10 mins, then it cools down naturally, 30 mins later it does it again. with the opentherm controller it fires the boiler to 50 odd, then keeps the pump running without calling for heat for a long time (40mins or more). the water going round slowly cools down to 30 ish or even high 20's, then it fires again if it needs to (which it doesn't always) . It keeps the radiators with some amount of warmth for all that time - seems to be trying hard to get all the last bit of warmth out of that water that it can, only firing boiler if it really really has to. the user feel is nicer - the temp drop rate during the non-firing still-pumping periods seems a lot less.

 

[Agile]

Nice to hear of an installer who has done what was expected of him.

Even if it took a while and a lot of pushing!

 

[D_Hailsham]

with the opentherm controller it fires the boiler to 50 odd, then keeps the pump running without calling for heat for a long time (40mins or more). the water going round slowly cools down to 30 ish or even high 20's, then it fires again if it needs to (which it doesn't always) . It keeps the radiators with some amount of warmth for all that time - seems to be trying hard to get all the last bit of warmth out of that water that it can, only firing boiler if it really really has to. the user feel is nicer - the temp drop rate during the non-firing still-pumping periods seems a lot less.

It's called "constant circulation" - very popular in Europe and the USA.