I saw posts in the range of $1400 for the vertex.

You will never get the usage information that you want because that is completely dependent on your heating load (meaning heating degree days, home size, heat loss, etc.)

Does the manufacturer recommend using this heater for space heating?

The vertex is a 76000 BTU heater. You will get about 72,000 out of it. Does this match your heat load?

Would a high efficiency condensing boiler make more sense?
Would a tankless make more sense?

I have seen tankless manufacturers mention using their heater for space heating... I don't know if it's a reasonable idea in practice.

Thanks! But do you have any experience with any of them as far as reliability, availability of parts etc? Tankless cannot work with this kind of system. The BTU of Vertex would work and it is noted to be used for this application. Know anything about Polaris? We want whatever to be used for both the water for the coils AND for potable, and I have read that no boilers, ether gas or electric can do that. efficiencies on record seem to be Polaris-95, Vertex-85, Bradford White-80.????

I don't have experience with any of these condensing heaters.

The website for the vertex was showing 90% but that might be hype.

Not trying to push it, but why wouldn't a tankless work in this application?

The condensing water heaters sound interesting... but are 50% more money than a tankless for a few extra percent efficiency gain.

Both the plumber and the company that put in our water space heat/ AC unit when the house was built both adamently say tanklass cannot work for this application. How can I dispute that? If you have any info to the contrary, I do not hesitate to be contrary to what people say.... I am trying to explore every corner of every option here. Vertex may have been 90% not 85, numbrs are swimming around now. Mostly I need folks to respond who have any of these as to their reliability. I know they are all expensive but if they are as efficient as they all claim and are more reliable than some of the people in the business here say, then they are viable options. It may be a matter of some experience someone had when any of them first came out that they are quoting,a nd now bugs are worked out. Obviously more technology usually begets the possibility of more problems but I really need info on if they are not masses of problems ordained to happen!
Keep the idea coming and thanks!

Greengirl,

When you say that you "want whatever to be used for both the water for the coils AND for potable", do you mean that the same water that is running through the hydro-air portion of the heating system, can also flow out of the hot taps in the house?

Generally speaking, "good workmanlike practice" would dictate that the water that is used in the heating portion of the system be isolated from the water used in the domestic hot water supply portion of the system.

Also, note that the high efficiency ratings of these water heaters are based on the use of them at domestic hot water supply temperatures, which are typically about 120 degrees. As you push the supply temp of these heaters higher, which you probably need because you woud be using one of them for space heating, they become less efficient.

Regarding reducing your propane USAGE, a 90% efficient water heater will consume 2/3rds of the amount of propane that your current 60% efficient model. At an average of $200 per month, a $2,000 high efficiency water heater installation job will give you a pay-back of about 2.5 years. But that assumes a 90% efficiency, which you are not likely to achieve with the water heater temp set to space heating temps.

As indicated in the other thread you started in heating and AC forum, because your electricity is so much less expensive ber BTU than propoane, if you went to a heat-pump heating system, the installation may be more expensive, and the pay-back longer (how much longer would depend on the installation costs), but if you look at it over the service life of the equipment, the heat pump would actualy be a better deal.

If your primary goal is to spend less money on fuel, then you need to cost out the heat pump installation and the anticipated operating expenses. Then look at the pay back time frame and the expected operating life of the installation. Compare that to the water heater.

Also, take the advice of your builder with a grain of salt.

The hyrdonic air heating systems were designed to do exactly that- use the same water for both, as it is completely potable by virtue of doign nothing more than circulating through a set of auxilliary coils over which the same air handler that the AC uses in the summer dispencses it. This is not a fringes kind of set up, it just isn't widely used in redidential but has been used commercially for many years.

Our issue is to save money as a by product of possibly changing the way we "condition" our air to not be using the MOST EXPENSIVE way to do it. It wasn't the original foremost thought. We thought that the water heater had to have gotten very inefficient over the course of 15 years, or that we had had a gas leak in the underground line from the tank for 15 years. Neither of those proved to be the case. gas comp(not cost) has always been this high. So either this particular water heater is a fuel hog, and supposedly any of them of that vintage should be compared to these new ones, or it has been suggested that it could have had a problem witht the cold wter inlet tube all along. Only way to find that out is to disconnnect and haul it out to check because it cannot be checkd in the palce it resides.
Hence the research into the ne high efficiency units that alas, cost some variation of the king's ransom. IF, and that's a big IF, they actually could save 1/3- 1/2 of the gas we are using , then one of them could be a consideration despite cost, since the idea of using water that is already always hot is sensible and the heat is great. If they would not save enough money to eventually make them worth it, then using this one till it dies and then going to a heat pump system seems like a better idea all around. Propane will not be going down but the electricity rate is so low that even if it goes up, it wil never catch up.
Brewbeer,
I have now talked to an actual Polaris dealer/installer who has done them for years and he says tht poor installation is the cause for most of the problems they have had. He also said that in their earlier years there were some design issues that have been changed, making them even better. I was trying to get a handle on comparing the others- Apollo, Vertex, and Bock. There is a Bradford White one that is made for this kind of air space heat as well, so I would welcome info on that as well, TW2.
Keep the ideas coming and thanls!