Opinions on Hot water sources wanted

[Pipestone Kid]

I am not an expert on water heaters, but I would strongly suggest you visit the Ridgid site (forum) and do a search on water heaters. The guys who post on there are mostly plumbers and have seen the pros and cons on most every heater made.

<https://www.ridgidforum.com/forum/forum.php>

 

[sodamo]

Just a guess, but I doubt the system you described can be bought as a functional, off the shelf system for anywhere near the numbers you provide, nor have I seen anyone describe a DIY on demand system. As for comparing to "off the shelf" solar HW, most numbers I've seen are cost prohibitive without rebates/tax credits.
If I am wrong, please provide a link to your system, as I'd like to buy one, otherwise can't say I see any meaningful contribution to the discussion. Just my opinion, others may disagree.

I have propane, on demand -Tagaki for over 6 years and happy . Wanted to do solar and have the Tagaki as backup, but solar quote was $4k after rebates and only did main part of the house due to length of runs. Actually we have 3 TK Jr at the house and another at the cottage.

David Sent from my iPad using TractorByNet

 

[dave1949]

In warm climates one of the cheapest and simplest solar water heaters is a batch system. Mount a steel tank where it gets sunshine and you will have heated water. There is no reason a batch tank couldn't serve as a pre-heater. I would think Hawaii would be a reasonable location for a batch heater or pre-heater for an on-demand unit.

 

[grsthegreat]

im ok with the idea of gas or propane whole house water heaters (however all 3 friends of mine that have them have all had to replace control boards that are very spendy).

I have wired up 3 electric whole house heaters in the past few years, and you couldnt give me one of those. They take 120 AMPS of power (3 separate 40 amp , 240 volt circuits) and even on 400 amp services the lights dim when its in use.

with all these systems, unless you have some kind of small water heater backup, you cant use a water recirc pump system. and i LOVE my recirc system. cant beat instant hot water at any faucet.

personally, on my house, i installed two separate 40 gallon super efficient, direct vent propane water heaters in series. The first one is generally the only one firing off, and the second one just stores already hot water. but its available if needed in heavy load periods. i never have run out of hot water.

 

[tkappeler]

YOu don't say how you are heating/cooling the house so I assume you are going warm air. A good option to the tankless is to go with a Condensing Wall Hung boiler and an indirect water heater. Rinnai has just introduced a package boiler water heater that is the balls. You could then use the boiler to drive a series of SMALL air handlers. That is the best way to zone a ducted system, imho.

AHNC, thanks for all of the details. The primary heat source is a high efficiency wood fireplace (Fireplace Xtrordinair Elite 36). Since we want A/C also so need the ductwork for that anyway, a heat pump for A/C and heat backup. I would love to do hot water heat again but I can't justify the expense of a boiler when I already have to run ductwork. So, it's a heat pump for us.

I am curious about a boiler driving air handlers. I am used to coils/heat exchangers in air handlers but that is freon. How would this work with hot water and air handlers?

 

[Robert_in_NY]

I'm not sold on tankless either and have been researching what to put into the house I'm building for my parents. New technology scares me. Tankless has a lot of benifits, but mostly if you use a lot of hot water and you have natural gas available. I'm still working on getting natural gas here, so that still might be an option. They hybrid and high efficient tank water heaters are also very efficient and cost effective.

Eddie

Eddie, what are you using for heat? I have an ECR gb97 gas boiler for heat (97% efficient) and run a boilermate hot water tank off of it. It is basically an instant hot water heater on steroids (mine is 100k btu). It will easily keep up with a 40 gallon hot water tank as you program the boiler to give priority to the hot water when the tank calls for heat. It isn't a cheap system but it is what I prefer for my own house. I put it in my first place and current house and never had an issue. The hot water tank will easily out last a standard hot water tank by a large margin plus it keeps your boiler in better condition by using it year round. The gb97 being an instant heater is great because you don't waste energy keeping a bunch of water hot 24/7. It only heats when it needs it. I can have 40 gallons of water heated from 60° to 120° in 20 minutes from start up. Once it is at temp it can maintain the temperature easily.

Another advantage is you only have one set of pvc vents sticking out the wall and one unit to maintain.

 

[Robert_in_NY]

AHNC, thanks for all of the details. The primary heat source is a high efficiency wood fireplace (Fireplace Xtrordinair Elite 36). Since we want A/C also so need the ductwork for that anyway, a heat pump for A/C and heat backup. I would love to do hot water heat again but I can't justify the expense of a boiler when I already have to run ductwork. So, it's a heat pump for us.

I am curious about a boiler driving air handlers. I am used to coils/heat exchangers in air handlers but that is freon. How would this work with hot water and air handlers?

There are options for central air using pvc for ducts or going with the Mitsubishi heat pump system where you have the compressor outdoors and can set individual heat pumps in each room for efficient heating/cooling room by room. This system works great in southern states but can't keep up with the heat demand of the northern states so you would still need a boiler or other central heat system. But the Mitsubishi system only needs a couple small copper pipes ran to each indoor unit. Very easy to install and efficient. Plus it gives you an easy way to control each rooms temperature individually.

 

[schweizer]

Other option for an electric heater is enough solar collector to power it, probably more complexity than you want to add on a new house.

Don't even think about that -- you would be very disappointed. Electric heating elements CANNOT be powered by solar panels. Well, in theory they can, but you would need so many solar panels that it is very cost ineffective. We live off-the-grid and know first hand all about living with solar PV panels, and what can and cannot (or should or should not) be powered by them. A grid-tied PV system can offset your electric use, but if you are using inefficient electric appliances, PV won't make a big dent unless you have a lot of solar panels. In winter time you can expect about 1/5 of their rated output. We have 3000+ watts of solar panels and on a rainy day like today their average output was 100-200 watts. PV makes most sense when you are very energy efficient.

We use a Rheem tankless water heater (RTG-84DVP) and have been very happy so far.

Marcus

P.S. Our tankless heater vents to through the wall, and the metal vent pipe also doubles as the air intake pipe. (it's a pipe within a pipe). It keeps operating down to about 1/4 gpm but needs about 1/2 gpm to turn on. The only problem we have it that it gets confused sometimes with preheated water -- it doesn't fire up if the incoming water is too close to its preset temp of 120*. Example: if our preheated water is 110* and the tankless heater doesn't fire up, I may get fluctuating too hot and too cold water in the shower. There are ways to fix that and it's an unusual problem for the manufacturer, so I can't fault them too much.

 

[AHNC]

You are certainly correct that solar DHW systems work well. If you have made your own, then good on you I was referring to a commercially manuf. & installed system. My idea for solar these days is to put a 3-5 kw system on the garage and tie it back into the grid. I hope to do that system next year...when the garage is built

 

[AHNC]

AHNC, thanks for all of the details. The primary heat source is a high efficiency wood fireplace (Fireplace Xtrordinair Elite 36). Since we want A/C also so need the ductwork for that anyway, a heat pump for A/C and heat backup. I would love to do hot water heat again but I can't justify the expense of a boiler when I already have to run ductwork. So, it's a heat pump for us.

I am curious about a boiler driving air handlers. I am used to coils/heat exchangers in air handlers but that is freon. How would this work with hot water and air handlers?

IF, you go with a ducted system make sure you have a third party test the system for air leakage prior to paying your installing HVAC contractor. This is commonly done on commercial systems, but rarely done on residential. I have a DOE report that says that the average duct system loses between 18-42% of its energy in duct leakage. Take the median number of 30%. Nice new 90% furnace X .7 = 63% efficient system day one. This is the problem with the Unitary manuf (Carrier, Lennox, Trane, etc). they can put all the technology they want in the duct system. They just cannot deliver it. As I said, I would look at either a Mitsu,or in my case a Fujitsu Ductless system. NO ductwork. High efficiency, NET TO THE SPACE with about 1/2% loss in the line set. I spoke with a contractor up in Susanville, CA some time back who had put in the HFI Fujitsu system next door to another house he did conventionally with hi eff, gas furnace/ac with ductwork. Install cost was about a push, but the HFI system was operating for less than half of the conventional system. Fujitsu is in Fairfield, NJ and have all the systems operating. Call first as it isn't an open showroom, but a training center, and look it over. In my home here in CA, there was a five yr old ducted system added to the house and it was the worst system I've seen in 48 yrs in the business. I pulled it all out and heat and cool with a combination of Rinnai Energysavers and Fujitsu mini-split heat pumps.

Driving an AH for heat is essentially the same as the AC side. You just put a heating coil in the AH and pump your boiler water to it. It still requires duct work, but you can go with small AH and small ductwork with individual systems in the home. this can work well as you can then zone the systems by area and use of the space. As well, you could do some radiant off the boiler if you choose to do so. How large is this house? What is the lay-out?