Welcome! Here are the website rules, as well as some tips for using this forum.
If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
how to descale nti combi heat exchanger (both sides)
I have a NTI TX-150 combi unit. It was a replacement to the original, and it looks to me like they used bad groundwater to fill the system initially 20 years ago. The replacement was just put in place, and the scale in the hydronic side has caused a few valve failures. One really odd failure was the spirovent has a little plug in the center tube of the core. That little plug slid down in the tube then got scaled in place isolating the pressure tank from the rest of the system...
Anyway, after a system flush with city water, I would like to make sure that the internal water to water heat exchanger (this is a combi unit) is clean.
I am currently having to reduce the flow rate of the city water to the houshold demand hot water, and I expect it is due to a partially plugged heat exchanger on the boiler side.
I did also do a vineagar flush of the demand hot water side, and did get some scale out on that side with the system off. The User manuals give NO instructions on how to flush that heat exchanger (or any of the system for that matter).
I did the pump in a pail with a bunch of vinegar for the demand hot water but I expect that would go thru the heat exchanger on one side.
I did a similar thing on the boiler side using taps in the external piping, but I have no idea if that would go thru this heat exchanger or not.
Taking it out looks a little messy, but I am up for it. Maybe there is a repair manual around somewhere for it, "he said hopefully".