HVAC-R tech here.

Not sure what you mean about simulating high temps on the thermostat. If you want to trick the thermostat into seeing a higher temp than it is actually at then you would need to find the temp sensor on the thermostat (usually a thermistor) and replace it with something where you can manually control the input like a potentiometer if there was a thermistor there.

If you’re talking about simulating calls from your thermostat to your hvac system, then you can usually do that with just some jumper wires if your hvac system has a built in transformer (almost all new systems do). You just remove the thermostat and jumper the hot wire (R or Rc) to whatever call you want to make.

Edit: I should probably note that if you accidentally jumper anything to ground or to common then you will likely trip the breaker or blow the fuse on your systems transformer. If you do that then you’ll need to find that transformer (usually in the airhandler, assuming a standard residential split system) and reset the breaker or replace that fuse before your system will work again.

Of course! I’ve actually used those for marine connections before. For some reason I just forgot those existed. Thank you.

Yeah, I’ll have to bring some of that along next time. We have it at the shop. I just didn’t consider bringing it last time because it hadn’t occured to me that heat shrink would be impossible to use in there until I was nearly done.

I don’t think a soldering iron would retain enough heat. I had considered warming something else up with a torch but any hot work anywhere in that site requires all sorts of permitting even where it’s possible.

I had never heard of that. Definitely going to look into it now though.

In this situation it was butt splices. We almost never solder anything. We just need the butt splices sealed in case of condensation or dirt.

There’s an idea. As long as I’m using boiling water there will never be an ignition hazard because it will never go much above 100C. I could probably do something with a bit of water and quicklime to have an instant ignition free hotplate.

I’d need to figure out specifics and test it elsewhere of course but that is probably workable. The real question is if it’s practical in the field. Either way it’s something I’ll probably try out at home just for fun.

Yeah, tape is fine here and logically I know noone will complain but it still rubs me the wrong way so I was hoping there was an alternative. If not then oh well, tape it is.