Home>Discussions>PLUMBING>Tankless Hotwater heater ????
9 posts / 0 new
Last post
BigWalt
Tankless Hotwater heater ????

I have few questions about tankless hotwater heater. It'll be natural gas unit.
I'm looking to free up tight space in 1925 house.

1... How heavy is it? [ average weight]

2....Do I need to change exhaust stack? I already have 40gallon tank hotwater heater with existing exhaust stack. It is not stainless steel, it looks like galvanized material.

3....If I change my mind about tankless hotwater heater, I can always install 40 gallon tank inside my crawl space [ plenty head room] but the exhaust stack "might" be the issue that will be holding me back.
I don't think it is good idea to run stack from crawl space and tied it to existing stack. [ I'll be straight up without any bends but I do know the first few inches / feet from heater must be at certain angle]
what do you all think?

sabo4545
Re: Tankless Hotwater heater ????

I have a Rinnai tank-less heater and love it. Mine runs on propane because natural gas is not available where I am. I can only speak for mine so other manufactures might be different. It weighs only about 40 or 50 lbs so it is hung on the wall. It vents directly through the wall. It has a pipe within a pipe. One brings in fresh air and the other exhausts the spent gases. You need the fresh air as the unit does not use air from inside the house. You would no longer need your stack and if it isn't hooked up to anything else could remove it to free up some more space. The only thing with a tank-less heater is they are considerably more to buy up front but since they are more efficient they will eventually save you money. Hope this helps you out.

i.m.plummin
Re: Tankless Hotwater heater ????

If you use Rennai be advised they have a proprietery vent. It is powdercoated stainless steel concentric vent and a condensation collector and roof termination kit. They do not give these away. They are one of the few who have an outside mounted unitand they also have a direct vent kit that doesn't req. the condensate collector. I have installed Takagi Reliable and more affordable thatn most. My fav. is Noritz their thermal exchanger is the heaviest gauge and their vent is more affordable than Rennai and they are more conservative in their Thermal rise output charts. If you have water that is high in minerals or corrosive do not buy one. I would instead rec. the Ruud Marathon. PB tank inside a 3" thick jacket of insulating foam. True bottom drain. Life time warranty and very efficient.

BigWalt
Re: Tankless Hotwater heater ????

speaking of vent.
Does it have to be vented to outside atmosphere or inside the house like regular water heater tank?
I just cannot use outside vent if I install tankless hot water heater in same place where my 40g hot water heater is.
On other hand, I've been reading and hearing different stories about vent location......what do I know???:confused:

I'm not going with LP, I'm using natural gas. It is what I have now and it is not cost effective for me to change to LP gas.

Can I use existing exhaust stack?

i.m.plummin
Re: Tankless Hotwater heater ????

Are you talking about combustion air? Because I know of 0 water heaters that vent into the house. If so then I doubt it. They need alot of air. You'll need to have a high+low of the appropriate size or select a unit that ducts in it own combustion air via approved vent. Which is usually the same as the exhaust. Only Rinnai has a combination combustion and exhaust vent.

Drake135
Re: Tankless Hotwater heater ????

Keep in mind if you currently have a tank hot water heater and you switch to a tankless, you may have to upgrade your gas line coming into your house. The amount of BTUs required to run a tankless is usually around 90,000. So not only will you have an up-front cost for the tankless, you might have an additional up-front cost to upgrade your gas line coming from the gas meter to inside your house.

Just something to consider.

rjdudley55
Re: Tankless Hotwater heater ????

Well, I switched from electric tanks to an electric tankless (Titan) and I'm free from having to deal with venting. I love the tankless. It's about as big as a phone book, weighs practically nothing, mounts on a wall and gives us scalding hot water.
Ray @ http://tanklesswaterheaters-howto.blogspot.com/

BigWalt
Re: Tankless Hotwater heater ????
rjdudley55 wrote:

Well, I switched from electric tanks to an electric tankless (Titan) and I'm free from having to deal with venting. I love the tankless. It's about as big as a phone book, weighs practically nothing, mounts on a wall and gives us scalding hot water.
Ray @ http://tanklesswaterheaters-howto.blogspot.com/

How is your electric bill?

How much is the unit?

By the way everybody.....friggin water heater is leaking now......
It is Rheem brand and it has plastic drain faucet. That faucet is leaking. I couldn't tighten it anymore without breaking the plastic faucet.

rjdudley55
Re: Tankless Hotwater heater ????

My electric dropped by at least 30%. And I attribute this to a couple of things. One is that the electric water tanks I had were just flat out not efficient. Having to wrap it in insulation is a good indicator that it's just not well insulated. Second is the fact that it's not cycling on and off all day long. Except for when I want hot water it NEVER is heating anything. To me they're everything they say they are. Again there are some considerations such as temp of the water coming into the house and the size of the house but there are units that fit all sizes of homes.
Hope that helps
Ray
And feel free to email me at [email protected]
http://tanklesswaterheaters-howto.blogspot.com/

By the Walt, I love that signature!!

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.