DISCLAIMER! When working with hot water heaters or gas stoves or gas cloths dryers unless you have ample experience working with Natural Gas appliances as I do. I suggest you refer to a licensed and insured professional. I worked for 2 years installing Fire Suppression Systems for commercial restaurant kitchens. I am more then comfortable taking on this home project. So please take this as a review of the product and the known unknowns this project produces. That being said, I hope this is helpful.
We moved in two years ago and the 70 gallon(i think it was 70) water heater was due for replacement. No problem, add it to the list of to-dos for our ‘fixer upper’. Aside from growing up with a tree hugging mom, as a bill payer I was annoyed at the thought of natural gas running continuously to maintain a tank temperature only to run out almost always after a shower or two, the dishwasher and or washing machine. Tank-less was on the scene and although still pricey I had to investigate. Sadly after an estimate or two from a licensed plumber at 2,000 to 4,000 dollars. I decided to ‘Do It Myself..
I researched and researched and found reviews for a Takagi (manufactured by Rheem) on Amazon that sounded pretty solid, and affordable. Under 500 dollars for a 3.8 gallon per minute Instant (tank-less) hot water heater. Even with a few hundred bucks for pipe and parts, tools n such, how could I go wrong.
Natural gas appliances produce carbon monoxide and must be properly vented (which includes proper ventilation design and sizing to accommodate usage (this part I was not experienced in but still confident I could sort it out). I removed the old tank and choose a location for the install (mounted on wall behind my dryer). Here is the thing, the tanked water heater exhaust was located above the boiler exhaust. The constant running of the hot water heater assisted the boiler in proper draft out the chimney. Once I removed the tanked water heater my boiler had draft issues and the CO safety switch over last winter routinely tripped shutting off our boiler. I did have a CO detector in the laundry that never sounded and two more on that floor and one upstairs that also never sounded. However you NEVER want to risk your family or yourself, who would. I will touch on ventilation in a bit.
I shut off the house gas supply outside again I am familiar, always refer to a professional if you are not qualified. I reran the black pipe (natural gas pipe) to my tank-less. shut off the water in the house and reran the water. Every was checked, double checked and we are ready to go. I turned on the tankless water heater which has a digital interface to choose temperature and display flow, in temp and out temp, very nifty. The hot water worked! BUT.. then it didn’t? I would take a shower the hot water would come but in the middle of the shower we were getting what we called cold water sandwiches (periods of cold water in the middle of our hot water) 🙁 It has been years since I used a multi-meter (an electric device to measure electric output at low wattage. So after weeks of futzing with it I finally called our plumbing guy ( I pay a monthly to One Call, free estimates and free visits ..) They were great and we determined that the computer board was shot DOA out of box. Takagi was great It had been over a year since I bought and finally installed the tank-less and they still sent me a new one for free. I was able to swap it out myself and BOOM continuous hot water for the past year.
The hot water NEVER runs out and there is no pilot eating gas when not in use. We noticed an immediate drop in our bill and we NEVER run out of hot water. OMG heaven!
Okay so now that the tank-less is working on to ventilation. The tank-less wasn’t all that difficult. I ran 4 inch PVC for the intake and the required z-flex for the exhaust. Not rocket science.
The boiler however because I removed the tanked the boiler exhaust did not have enough umph to start the draft. I was missing the chimney liner. So this season, 2019 I added a 6 inch chimney liner. Our boiler is direct vent compatible, I connected the liner directly to the boiler and voila!
Water heater 700$ – was estimated 2,000 to 4,000 saving 1,300 to 3,300$
The liner about 200$ – was estimated 2,000 to 3,000 saving 1,800 to 2,800$