Cylinder stat, two immersion heaters and iBoost

[BMcN]

Just started wiring in my ASHP and cylinder.

 

The ASHP came with a boost kit for the immersion but I would like to do away with that and use my iBoost.  

 

Now the tank has a middle and a lower immersion and has a stat placed in the middle of these.  The stat has a control and a limit set of contacts.

 

My question is what is the best way to wire this?  Obviously the ASHP uses the two stat settings in series.  My thinking was to use the upper limit through a relay for the iboost on the lower immersion?

 

Any clarification would be good.  Thanks

[dpmiller]

The iboost monitors both outputs- it heats on no1 until that heater's stat is satisfied (or any series switch or relay you may have switches open) then it heats no2, but "tries" No1 every 15mins (IIRC) to see if it's requesting heat again.

I've set mine -a thermal store- to master on the upper to heat to DHW levels quickly, but then the switch over to the bottom element to fill the rest of the tank.

[ProDave]

Connect the iboost to the bottom immersion heater

 

Connect the ASHP immersion control output to the top immersion heater.

 

The cylinder thermostat plays no part in the immersion heaters,  It probably pays no part in the normal control of DHW from the ASHP. That usually has a temperature probe for that.

 

But the cylinder thermostat must be wired as a safety device to shut the motorised valve to the cylinder if it is triggered.  It will normally never do that, but is there to stop the cylinder overheating if other systems have failed,

[BMcN]

2 hours ago, dpmiller said:

The iboost monitors both outputs- it heats on no1 until that heater's stat is satisfied (or any series switch or relay you may have switches open) then it heats no2, but "tries" No1 every 15mins (IIRC) to see if it's requesting heat again.

I've set mine -a thermal store- to master on the upper to heat to DHW levels quickly, but then the switch over to the bottom element to fill the rest of the tank.

I did read that in the manual, use the upper as HRT1 and lower as HRT2 and yes I think it was 15min.

 

1 hour ago, ProDave said:

Connect the iboost to the bottom immersion heater

 

Connect the ASHP immersion control output to the top immersion heater.

 

The cylinder thermostat plays no part in the immersion heaters,  It probably pays no part in the normal control of DHW from the ASHP. That usually has a temperature probe for that.

 

But the cylinder thermostat must be wired as a safety device to shut the motorised valve to the cylinder if it is triggered.  It will normally never do that, but is there to stop the cylinder overheating if other systems have failed,

 

The manual does show the ASHP going through the separate stat, I have attached the wiring config I am going for (not including the iBoost).  The supplied stat looks pretty generic like this.

 

So you would have the ASHP to upper, setting the limit on the immersion itself (around 50 degrees?).  iBoost to the lower stat, setting the limit on the immersion (but to say 70degrees?).  Then have the stat wired as separate safety device to stop all DHW heating?

[ProDave]

34 minutes ago, BMcN said:

I did read that in the manual, use the upper as HRT1 and lower as HRT2 and yes I think it was 15min.

 

 

The manual does show the ASHP going through the separate stat, I have attached the wiring config I am going for (not including the iBoost).  The supplied stat looks pretty generic like this.

 

So you would have the ASHP to upper, setting the limit on the immersion itself (around 50 degrees?).  iBoost to the lower stat, setting the limit on the immersion (but to say 70degrees?).  Then have the stat wired as separate safety device to stop all DHW heating?

Yes wire it as shown, all detailed for you.

[BMcN]

As shown here, the ASHP isnt connected to immersion and is using the cylinder stat.  

 

So keep this way and let the iBoost do both immersions? (and a timed boost for bug killing duties).