I have a WEIL-McLAIN furnace that provides baseboard heat and hot water for the home - We have well water and septic.
Early this year I experienced water leaks due to low water PH and so I decided and installed, 3 months ago, a water neutralizer (uses calcium). Over the last month or so the hot water pressure, NOT the cold, has fallen so dramatically that taking a shower or washing dishes has become a challenge. And so something has to be done very, very soon.
Here are some of the options I'm considering: Replace the Coil? Flush the coil? Replace the furnace?
Not sure what's the right thing to do. I would appreciate your suggestions and ideas. Thank you

I would descale and flush the tankless coil first. Often there is a flow restrictor that has became partially clogged. You could pipe another heating zone to a indirect fired water heater and have unlimited hot water if the descaling doesn't provide adequate hot water for your needs.

I had a similar issue recently, and I determined it to be mineral deposits in my mixer valve in the basement near the boiler. I got a repair kit, new seals, etc and good as new. That was after I had replaced the valve cartridge on the shower valve. The shower was the one point in which i had drastically noticed the temperature and pressure difference.

it could be the mixing valve but i would think you would notice a change in the hot water temperature.
i would look for debris in the flow restrictor located in the cold water supply to the tankless coil.
most common type looks like this...

Thank you all for the suggestions.
I looked for the water mixing gadget but couldn't find any. I'll have the oil guy come to check the system and see what he has to say and let you all know.
Thank you again



Edited 1 times.

The service man confirmed the problem is scale build up in the furnace's hot coil, and for sure the new neutralizer is the culprit.

At this point I've decided the best course of action for me is to bypass this furnace coil altogether and install an indirect hot water heater, cost ~$2k. Not exactly what I had in mind but the more I think about it the more it makes sense. In fact I think I should have done this many, many years ago - acidic well water and furnace hot coil, for the house hot water needs, just don't go well together.

And by the way, the price tag for replacing the furnace coil is ~$1k unless you can do it yourself, then the price goes down to ~$300 + aggravation.

Thank you all for your comments and help and until the next time Merry Christmas and Happy Holidays