Remeha Avanta15v with vented cylinder and isense

[revo68]

I have just installed a setup that dumbrill posted a few years ago but I have one small fault, I cannot get the boiler to provide hot water. I have a tank stat instead of the thermistor, a time clock for the DHW and a sauter 3 port valve wired up as a diverting valve. On initial start up the boiler repeatedly switches over the valve as it completes it's checks, but with the heating off and the DHW on the valve does not switch over. I have checked and there is power at terminal 3, block X2 (from time clock) for DHW, but not on terminal 2, block X5, which should switch the 3 way valve over.
I have tried everything I can think of and was hoping someone on here may be able to give me some pointers.

Read more: //www.diynot.com/diy/threads/r...-cylinder-and-isense-rf.326808/#ixzz3mwzwf6Qt

 

[picasso]

Do you have the 3 port valve the correct way round as on the schematic ? A to dhw and B to heating.

 

[revo68]

Yes, swapped the valve around and triple checked wiring. I'm scratching my head over this.

 

[picasso]

Terminal 3 on x5 is the call for heating (not used in your case) terminal 2 on x5 is the call for hot water, you call for hot water using the isense, call you post up a diagram of what you have done?

 

[revo68]

That's interesting that you say you call for hot water via the iSense. The instructions for this are not clear, I was assuming that because I have used a tank stat that the water effectively would be controlled via the programmer. The iSense asks for a temperature set point or time clock, but with a temp set point as well. Surely the tank stat will either be NC or NO depending on the temp of the tank.
The diagram that I worked from is option 6 of the remeha suggested schematics. Uploaded a photo with slight alterations but unsure how this will look.

 

[hertsboilers]

Do you have the 3 port valve the correct way round as on the schematic ? A to dhw and B to heating.

Hi picasso, A to air and B to bath?

 

[picasso]

Do you have the 3 port valve the correct way round as on the schematic ? A to dhw and B to heating.

Hi picasso, A to air and B to bath?

Not on this set up, I think its to give priority hot water when energised and returning to heating (pulled back with the spring)when dhw satisfied, to the op I think you still have to set a water temp on the opentherm wont recognise a call for heat.

 

[revo68]

i don't have time to try out just now. Will have a play tomorrow and report back. Many thanks for you interest.

 

[D_Hailsham]

Have you set parameter P4 to 0? This turns off ECO mode, which is necessary when heating a cylinder - see the Installation Manual.

The boiler knows if a thermostat or DHW sensor has been fitted and passes this info to the iSense. I wouldn't be surprised if the iSsense uses this info to decide if it needs to ask you for a DHW temperature when you are setting up the HW clock program.

If you have a DHW sensor the boiler automatically raises the boiler temperature by 15C above the required DHW temp (it's set by parameter P31).

If you use the iSense to control DHW, you will have to set parameter P3 to 1.

 

[revo68]

Many thanks Mr Hailsham for your input. I was sure that when I got home tonight and tried you suggestions that the problem would be sorted, but I'm afraid nothing has worked. My parameter on P4 was on 2, regulated by controller, according to my manual. I set it at 0 and set the time clock to constant, made sure the tank stat was set high enough to call for HW and waited, but to no avail. Played around with P3 settings as well but still no success.
I did originally have a thermistor on the tank which I thought was the right one but removed this because it was giving totally the wrong temp display, and resorted back to the stat. Do you think the iSense would need resetting after this change?

 

[D_Hailsham]

Set parameter P6 to 1. You will then be able to see more status info instead of just the two dots - see para 2.10.5 in the Installation Manual. You can also read the actual flow and return temps and other data by pressing the + button - see para 2.10.6. Incidentally what is the value of parameter P1?

I don't know about resetting the iSense, but it might be worth resetting the boiler, parameter PdF and PdU - see boiler's data plate for values. You will then have to re-input any parameter changes you want to make.

 

[picasso]

Which sauter valve have you installed ?

 

[revo68]

Success tonight. I changed the parameters that you suggested D Hailsham, and then turned the boiler off then on. Also reconnected the iSense to the base station and hey presto the boiler switched over to DHW. Still testing it out tonight and trying to get my head around what is relevant on the iSense.
Just for information Picasso, the sauter valve is a B322D wired up as a diverter valve using blue/neutral and grey & white cores as the switched.
Many thanks for ALL of your help, I don't think I would have sussed it without you.