Garage Ventilation

A few over generalizations here like tankless are not going to be efficient. Just saw an efficient unit on This Old House that was vented with PVC pipe (very efficient) and would handle about 15 GPM so they are out there. I didn't see the brand but this is going to be expensive. Not your average tankless unit. You really have to look at your particular situation and needs when looking at units. I think the claim that tankless is more efficient without looking at other factors is bogus too.

One problem with a lot of tankless units is the limited flow rate, especially with low incoming water temp as noted before.

I installed a large condensing, tank type water heater to supply heat for radiant floor and large shower. PVC for air supply from outside and flue vent. I plan to interlock the floor control so it doesn't come on during showers - it pulls the temp down some and affects SAF. Otherwise it is great.

I also installed a drain line heat recovery device. Interesting unit with no moving parts. The drain line from the first floor goes through the basement right by the water heater so plumbing was easy. It goes in the drain line and has copper tubes wrapped around the drain pipe with water from the street going to the water heater. The water is preheated by the drain water. They claim up to 60% recovery and it does recover a lot of heat. I got mine just before copper prices started shooting up about 8 years ago and they have switched distribution but they look to still be available:
http://gfxtechnology.com/
I have no connection with the company other than buying one of their units and being happy with it.
 
Don't get a tankless if you think it is going to save you all kinds of money in efficiency. They really don't. They do provide endless hot water, they take up virtually zero space, they don't leak (just don't let them freeze), they can be located in many more locations, and they are zero maintenance. Those are the reasons IMO to consider a tankless. In new construction in a milder climate, I would never do it any other way. In a retrofit, you need to look at your particulars.

When I went tankless, the unit I replaced was a crappy electric. I went to a Commercial level Bosch (used for apartment buildings). I ended up saving $50ish/mo (trying to remember from a few years ago).

--Dan
 
I'm sorry, when I said there won't be a huge savings, I was referring to buying a new high efficiency tank style and comparing it to a new tankless unit. Certainly if you replace an old inefficient POS unit there will be a significant savings. Especially if it is an old electric resistance unit.

It is also hard to compare electric to gas fired. Electricity prices vary tremendously accross the country, so if you are talking about efficiency in the money sense, it would be different then if you talk about efficiency of energy consumption. Also there are the heat pump electric units which are quite efficient and very cost effective if you live in a relatively low cost electric region. Electric resistance heaters are "100%" efficient, but that is sort of a bogus claim becuase electricity is not a natural resource, you have to make it and deliver it, and that process is far from 100% efficient. So when I hear someone say electric resistance is more efficient than an 85% gas unit, I have to tell them they are a bit mistaken. Electric heat pump units will be about 3 times more effiecient than a resistance unit. They do blow cold air into your house, which is great if you live in a warm climate since you are kind of having a little AC unit there that dumps the condensor heat down the drain (as opposed to outside air). If you are heating your house most of the time, I don't know just how well that works out.
 
Good points Lou! That's what I like when chatting with you, the back and forth!

And it was an older POS electric. At the time, I got the unit cheaper as well since my wife was the showroom manager for the residential side of a local plumbing place. Sure wish I could go back and NOT install the tankless unit and the Fireplace. Bring them with me to my new house. I do miss them.

:-(
 
Good points Lou! That's what I like when chatting with you, the back and forth!

And it was an older POS electric. At the time, I got the unit cheaper as well since my wife was the showroom manager for the residential side of a local plumbing place. Sure wish I could go back and NOT install the tankless unit and the Fireplace. Bring them with me to my new house. I do miss them.

:-(

Cool. I love bantering about on this stuff.

I have to say, I am quite pleased with my tankless units. They take up zero space (mounted in the wall stud space) and are close to point of use. I also expect them to last 20 years or more and never leak into the house (they are mounted on the outside of the house so even if the did leak it would go outside).

However, at times I wish I put heat pump units in with large tanks and a recirc pump. You can't really do recirc pumps with tankless units (sort of possible but not easy) and I wish I had that nearly instant hot water of a recirc system. Plus, the price of propane keeps going up (more so than e) and with me cooling the house most of the year, the heat pump dumping cold air into the house would be a welcomed deal.
 
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