i have a takagi that has performed flawlessly for about three years now.
the downsides are that it takes a little longer to get hot water from the other side of the house. my kitchen is the furthest from the tankless system and can take about 30 secs to get hot water. the thing also needs an electrical plug nearby to start the flames if you go with a gas unit.
the plus sides includes:
- no water tank to collect sediments. this means drinkable hot water...but i never do.
- no water tank to rust out...ever.
- i think it has a 7 year warranty but reports have gone where they last 20 years plus.
- it means that my wife, a guest and myself can take spearate showers and have the diswasher running and never getting a cold burst of water or ever running out of hot water. you also dont feel a temp change when someone flushes the toilet.
- lower gas bill as you only heat the water when you use it and need it. no big deal for me since gas is so much cheaper than electricity but at least the hippie in me makes me think i am making less greenhouse gases.
- smaller footprint. i have mine mounted outside on the back of my house. it takes zero ground space
i have NEVER ever experienced what rjd experienced with my tankless system. when i am taking a shower and someone else turns on another faucet for hot water, i feel the slightest change in temperature...it is then quickly compensated by the flow meter and computer of the tankless system.
i would never get a tank system again. there are just way too many advantages when you get a great tankless sytem working properly.
cost on average is about $1100 or so for the unit i described. you may be able to find a plumber to install it or takagi (if you go with them) can locate one for you. they are based in irvine. cost of install? on average, i was quoted $800 plus parts.
the best tankless sytem out there is probably noritz, then takagi then bosch. i have no busniess affiliation with any of them and my opinions are purely based on my own experiences.