Author Topic: Tankless Boiler/ Water Heater Combo  (Read 26763 times)

El Dueno

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Tankless Boiler/ Water Heater Combo
« on: June 29, 2012, 11:47:53 AM »
I'm considering upgrading my separeate Furnace (from the 1950s) and my Water Heater (3 years old) to a tankless Combo unit. The house is gas, heated by radiators.

The only tankless system I know about is the Baxi Luna, which was on HGTV Income Property. I got a quote for like $6500 to install that system. I've done some googling but havent found many comparisons or reviews.

Does anyone use this system or another comparable one? How do you like it? How many bathrooms do you have in your home? Are your showers cold if you have multiple showers going on at once (or shower + dishwasher/ washing machine)?


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Re: Tankless Boiler/ Water Heater Combo
« Reply #1 on: June 29, 2012, 11:55:45 AM »
We installed a Navien system last winter. Our house is a 1950's raised ranch, with 2.5 bathrooms. We have had no problem with cold water 'shocks' or pressure when there are 2 showers / dishwasher running at the same time. Our system was eligible for an energy rebate and cost $2000. Overall we are pleased with our tankless system.


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Re: Tankless Boiler/ Water Heater Combo
« Reply #2 on: June 29, 2012, 12:01:38 PM »
There are tons and tons of tankless hot water heaters. My home improvement store has them, and a google search will turn up a ton of them. It may not be worth it to upgrade such a new hot water heater for a tankless one. Michael Bluejay has a nice page about whether it'll save you money or not, and you could probably adapt his equations if you wanted to be really precise.

El Dueno

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Re: Tankless Boiler/ Water Heater Combo
« Reply #3 on: June 29, 2012, 05:24:35 PM »
Thanks for the replies!

Irishman: Is your Navien system just a water heater or water heater/ Boiler combo. I'm definitely trying to find more about the latter. Was the $2k for just the unit, or install as well? Also, was the $2k before or after your rebate?

Thanks again!


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Re: Tankless Boiler/ Water Heater Combo
« Reply #4 on: July 01, 2012, 03:06:00 PM »
I got a 1.6GPM propane water heater for $170

I had originally got a 4.23 GPM unit for $340, but it was WAY more heat and flow than I could ever need.

As it is, if I turn it all the way up it is painfully hot.

My gas use is easily less than 1/2 what it used to be, even though I take much longer showers (the hot water never runs out!!!!!!) with no change in pressure.

It was pretty easy to install, all I needed was about $10 worth of plumbing parts.

I don't have a dishwasher or washer or multiple showers, so I can't say exactly, but I'm sure the larger unit I had first could have handled all that.  Not sure that it would be worth the money though - why not just wait until after your shower to run other appliances? 


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Re: Tankless Boiler/ Water Heater Combo
« Reply #5 on: July 22, 2012, 03:36:22 PM »
A few things to think about here.

First, how cold is the cold water that comes into your house in the winter?  In the north where I live water comes in at around 40 degrees F in the winter so I'd need a much bigger tankless system to get it hot enough than if I lived in the south and water was 50 or even 60 degrees coming in.

Second, how much do you need to heat your house?  I don't know the gpm that would be sent to your radiators, but I'm assuming it is a lot.  While you can pretty reasonably not run multiple showers and the dishwasher at the same time I think it would be a lot of trouble to ensure that your heat doesn't go on while your shower is running so you'll need to size the unit to be able to feed both the radiators and the shower at the same time. 

Both of these could lead to your needing a fairly large unit that might be expensive.  One of the reasons a unit like this can be pricey is that gas pipes generally need to be re-run to install it, and you need to install a solid vent too.  I'm curious what sort of vent Bakari put in for his 1.6 GPM unit, probably nothing too huge, but if you're heating the whole house and need a big unit you will need a big and well installed vent to deal with the exhaust.  If you can deal with a small unit you might also consider an electric unit, electricity costs more than gas to heat, but it's super simple installation (for a small unit where you don't need to add a new breaker) could make it worth it.

Another thought that might be good for you is to look into solar hot water/boiler combo.  These systems are the most cost effective way of putting solar on your house and if you live somewhere warm they have the potential of providing hot water and heating with no ongoing costs (but obviously a large upfront cost).  There is so much variation on the cost of these that if you're interested I really recommend talking to someone locally who actually installs them so they can tell you what works best for your climate.

You could also just stick with your current heater (that's what I'm doing) for a while longer.

Whatever you do, definitely put in 1.25 GPM shower heads like MMM recommended, they will reduce your hot water flow needs and let you buy a smaller system (whatever kind you choose).