Idea for a betting pool

[LarrylLix]

I have 1710 sq. ft. main plus basement, slightly less. Water heater is at the end of the "L" next to garage to get venting. The long runs are a bit of a mistake for hot water travel. Coupled with everything water-saver it takes about 60-90 seconds to get hot water to the kitchen tap. Dishwasher gets hot water quick as there is no water-saver restrictions. I put in a manifold for both hot and cold but the hot is a mistake. By the time the hot water hits it, heats it up, and runs down the long PEX it takes forever. The manifold will come out with a tree structured feed maybe this winter. Many have installed circ pumps for "instant" hot water feed constantly in the main pipe. There is a scheme to make that work using a small tank, somebody posted on a forum somewhere.
 
My old tankless (Rinnai) took 0.6 gpm to turn it on and off. The newer unit (Rinnai) takes 0.6 gpm to turn on and 0.4 gpm to turn off. That doesn't sound like much flow. I measured about face washing flow = half on from a water-saver faucet. But... you probably have waters mixed less than 50% hot when actually using. The tankless only sees that portion.
 
My units were both 15,000 to 180,000 BTU. Yeah go for the biggest and bestest capacity you can get! Wrong!
The bottom end is more important to wash your face with low flow than having three showers at once! Watch the gpm rating as it is based on a certain temperature rise and if you are on a well your water comes in at about 50F and the flows are way down for bragged ones. Get to know the BTU formula. It's pretty easy (in USA terms) and I think Wikipedia has the answers there.
 
Then there is the venting. The Rinnai unit takes double wall concentric pipe. A friggin' elbow in Canuckistan is almost $100!  and that is from the plumbing wholesalers as a contractor. Yeah I cross border shopped for those at about 25% of that price.
 
The Rheem unit sold at homedepot.ca takes two cheap white PVC ?? pipes tht are much easier to install. My neighbour installed one of those in a very smallhouse this year and he is happy so far. He is running hydronic baseboard so his needs are different than mine with just on or off.
 
Remember the price of the tankless may not be the major expense in the thing depending on your venting. I had to destroy my first unit removing it 'cause the snow fell six feet over the outlet one year. The aluminum inner pipe was welded together from the gas fumes corroding the aluminum. It's the same old gottcha'. It the price of the accessories that kills ya'.
 
I hope your LPG is cheaper than your electrical energy. Our's runs about the same so no break would happen there and most elect. people in the rural are running elect.  heat pump t get consumption down.

 

[NeverDie]

My old tankless (Rinnai) took 0.6 gpm to turn it on and off. The newer unit (Rinnai) takes 0.6 gpm to turn on and 0.4 gpm to turn off. That doesn't sound like much flow. I measured about face washing flow = half on from a water-saver faucet. But... you probably have waters mixed less than 50% hot when actually using. The tankless only sees that portion.
 
My units were both 15,000 to 180,000 BTU. Yeah go for the biggest and bestest capacity you can get! Wrong!
The bottom end is more important to wash your face with low flow than having three showers at once! Watch the gpm rating as it is based on a certain temperature rise and if you are on a well your water comes in at about 50F and the flows are way down for bragged ones. Get to know the BTU formula. It's pretty easy (in USA terms) and I think Wikipedia has the answers there.

 
The last time I looked into tankless (2009), it seemed that running two smaller capacity tankless units in "tandem mode" was a way to mitigate the minimum flow problem.  In the low flow scenario, only one of the two fires up.  The second one ignites if and only if demand is greater than the heating capacity of a single tankless. A data cable runs between the two units to coordinate.   As an additional side benefit, I also liked the idea of having the redundancy, so that if one went bad I could bypass it and limp along on just the other until the bad one could be repaired/replaced.  Not sure how things are now, but in 2009 tankless units seemed prone to having problems, or at least I got that impression, so in that context the redundancy might have real value.
 
As for cleaning the scale out twice a year, I remember hoping that a water softener (which we were already installing for other reasons) would either entirely eliminate that need for descaling the tankless or at least greatly reduce the needed frequency.  Anyone happen to know if that's so?  I seem to recall that a sticking point on the contract was that even if the softened water rendered the need for descaling moot, the warranty would be voided if we didn't do the descaling anyway according to a predetermined schedule, because that was how the warranty was immutably written.  Sound familiar to anyone?  With benefit of hindsight,  maybe it was just the plumber bluffing me so that he could get paid lucratively for maintenance work that wasn't really needed.  I remember thinking that the cost of that recurring maintenance more than offset any cost savings in natural gas, and it became a deal killer.

 

[LarrylLix]

The tandem idea is very novel but the proper way would have been to have gas burners that do down to about 5,000 BTU. That would solve most of those minimum  problems.
 
Water softeners does not solve the clean out issue. They do however reduce the amount necessary. In my previous house my water ran about 48 rains of hardness. You would have to clean a tankless out at least every month. Think kettle bottom x100.
 
In my current house I have a grit and dirt filter, an iron filter with an oxygenator to make it more efficient, and a water softener that doesn't do much. My well water was tested at 19 grains, and as the well was used at 14 grains and now 11 grains of hardness. With that small amount of sodium ion exchange you can drink the water and not even taste the sodium bitterness. I grew up with water softeners as a prerequisite so I am familiar with the feel and taste of hard water in the shower, the old way of detecting water softener rejuvenation needed again.
 
If you have ever run sodium exchange softened water into a humidifier you will know that the maintenance is not over an still has to be done. The residue is not a hard cake-like calcium / lime but a slimy semi-firm jelllo like gunk. I think the biggest problem with it is the flow and other sensors get clogged blind, maybe.

 

[Desert_AIP]

This thread is timely.
Came home last night and a tree branch had taken out both power and the phone line.

 

[NeverDie]

The tandem idea is very novel but the proper way would have been to have gas burners that do down to about 5,000 BTU. That would solve most of those minimum  problems.
 
Water softeners does not solve the clean out issue. They do however reduce the amount necessary. In my previous house my water ran about 48 rains of hardness. You would have to clean a tankless out at least every month. Think kettle bottom x100.
 
In my current house I have a grit and dirt filter, an iron filter with an oxygenator to make it more efficient, and a water softener that doesn't do much. My well water was tested at 19 grains, and as the well was used at 14 grains and now 11 grains of hardness. With that small amount of sodium ion exchange you can drink the water and not even taste the sodium bitterness. I grew up with water softeners as a prerequisite so I am familiar with the feel and taste of hard water in the shower, the old way of detecting water softener rejuvenation needed again.
 
If you have ever run sodium exchange softened water into a humidifier you will know that the maintenance is not over an still has to be done. The residue is not a hard cake-like calcium / lime but a slimy semi-firm jelllo like gunk. I think the biggest problem with it is the flow and other sensors get clogged blind, maybe.

 
Here the tap water is around 11 grains.  The water softener takes that to zero grains.  
 
I'm not sure an evaporator is a good model for what to expect from a tankless though.  There's constantly fresh water flowing through the coil in the tankless, and being a soft mineral the potassium (in our case, sodium in yours) I'm hoping it might redissolve whenever there's flow below the minimum needed to trigger ignition, or even just sitting there in the coil between ignitions.  For instance here we don't get potassium buildups in our showers because the fresh water in each new shower dissolves away any evaporated potassium residue from the day before.  Our pots in the kitchen don't get potassium buildups either, because we rinse them out after boiling water in them.
 
Ideally the plumber  on This Old House would have cross-sectioned a retired tankless that had been fed its whole life with softened water and never descaled.  Then we'd have an empirical answer.  It's irritatingly difficult to get basic info like this that's reliable.  The best info seems to come from chance encounters with people who actually own the equipment.  That's why posts such as yours are so helpful.
 
Anyhow, it's more than merely academic for me.  When the current tank units fail, I'd like to  have a plan already worked out as what I'll be replacing them with.

 

[mikefamig]

Neverdie
 
Right now my spare time is all used up with installing the Elk and UPB stuff. I haven't really given any thought to replacing the water heater and just mentioned it in passing. When I do turn my attention there I think htat I may just go with another electric heater with a smaller tank. They are more efficient these days and there are only two of us in the house so we don't have large hot water needs.
 
While the electric heater is expensive it may be better than all of the time pain and money involved in converting. I'm sure that it's a big can of worms and I'll have some reading to do before making any changes here.
 
Mike.

 

[RAL]

One option to consider for an electric water heater is a heat pump model. GE GeoSpring is popular.  A.O. Smith also has similar models. 

 

[mikefamig]

One option to consider for an electric water heater is a heat pump model. GE GeoSpring is popular.  A.O. Smith also has similar models. 

I had a heat pump added to my electric water heater over ten years ago and I didn't like what it did to the atmosphere in the basement and I didn't see much improvement in the electric bill. I ended up removing and trashing it.
 
Don't get me wrong, I'm not against heat pumps. I bought my house in 1996 and it had electric fired forced air heating system backed up by a combination air conditioner/heat pump that was over 20 years old. Long story short I converted to an oil burner and it was no cheaper to run than the electric/heat pump and I regretted converting. Now I burn wood pellets and use the oil only when I need to get some oil out of the tank before it gets too old to burn. I've gone as long as 5 years without buying oil.
 
Mike.

 

[LarrylLix]

Yuk!
 
Energy sources must be very area dependant.
 
Here, people with Oil anything want off so bad it pays for itself in about 1 year. Propane may be somewhat cheaper but still nasty and used by most rural people that have nothing other than electrical energy. Some have gone to electric heat pump and with it's 3:1 COP competes against propane. Our NG is the cheapest.
 
With NG heating (hydronic), stove, dryer and 3kW of PV my NG bills peak at about $130 / month in winter and dip to $50 / month in summer. Electrical energy is still almost double with mostly lights (almost all LED) and TV (LED)
 
My B-I-L complains his oil bill is about a 1 +  2/3 tank each year. At about $1000 per tankful that hurts. That was also when he burned a couple of cords of wood each winter. His air source heat pump doesn't seem to do anything but I am sure he doesn't understand the dual contact thermostat. The fireplace is shut down due to wife allergies (yeah, some good jokes there) so we'll see what he pays this year.