heating with hot water on demand.

[phil]

I spoke to a friend who has this system. The basics are that he replaced his heater and his water tank with a big natural gas fired hot water on demand system. the hot water heats some water coils in a heat exchanger, air is blown through into his existing ductwork and heats his house. I guess old radiators could also be used. It sounded interesting, perhaps quite efficient.
my hot water tank and furnace are both really old and both are vented up the chimney , no flu just the brickwork. so I'm curious about learning about converting that way rather than buying a new tank and furnace.

[Manalto]

Thanks for posting this, Phil. I've also spoken with a couple of people about using the system and the jury is apparently still out. A builder I know recommended an electrical (on demand) system for my cast iron radiators but warned me that this type of boiler requires more maintenance. A couple of professionals have told me that they can be troublesome. Maybe by now the kinks have been worked out of them? It's a really appealing technology, if reliable. I'll be interested to hear from others, who have had some experience with on demand, on this topic.

[GinaC]

On the flip side, I've stayed with a family here in Vermont who switched over to hot water on demand and they hate it. You have to keep the temperature below a certain level to abide by federal laws, and it's just not worth the trouble.

I do know that I had to wait a long time to get the water hot enough for my shower there.

My own hot water heater is operating beyond its life expectancy at the moment, so I just ordered a nice Rheem 8 year one.

[phil]

thanks Gina. Its good to get the input.
My neighbor installed one, she has a suite for her mother and it's in there. she said although it isn't super loud it does make some noise in the suite every time someone uses hot water so maybe location is important.

I watched an installation video, It looks like a bit more than a weekend job and I assume many find theirs leaks and then are in a rush to get life back to normal. of course just replacing the tank is less complicated so If I do go to on demand then Id need to plan to do it before mine fails which could be soon or who knows how long.
hate the idea of these new ones that fail so quickly. at our summer place we still have an old one made of actual brass and it still works after so many years. Its got to be at least 60 years old. There is no reason why we should have to throw them in the landfill after such a short life expectancy.

[DRJR]

I have electric on demand hot water here at the Rotten Ranch. Works great, 10 years trouble free.
No more running out of hot water from the leaky old hot water tank.

Now to use this set up to heat a house, I can't say how it would work. I would look for other options myself.

[Manalto]

Thanks for the positive feedback. Who is the manufacturer of your system?

Now to use this set up to heat a house, I can't say how it would work. I would look for other options myself.

The rationale for using on demand for heating is the location of my house and the unpredictable nature of winters there; on the Gulf Coast, it could be 35 degrees one day and 75 the next. On its face, this method seems like the least wasteful way to supply hot water to my cast iron radiators. I think...

[1918ColonialRevival]

Hot water on demand is basically what a circulated hot water heating system is. In a heating system, it's a closed loop, meaning the water is already in the system and it is not drawn "cold" the same way that water for a tap is, nor is it stored hot in a tank. The temperature falls below the thermostat setting, the boiler kicks on, and the water is heated as the circulator pump moves it through the system. When the room temperature is warmed to the desired level, the boiler kicks off and the circulation stops. The cycle repeats when it is cold enough for the boiler to kick on again. Oftentimes, the water in the system has not cooled to room temperature when this happens.

For boiler efficiency, gas and oil are usually better than electric. A good gas or oil unit will have around 84% efficiency or so. The last time I checked, average electric units were a bit lower. Some electric units will advertise 90% efficiency or better, but you'll pay dearly to run them.

As for hot water on demand for kitchens and bathrooms, I've heard that it works better for smaller applications (and a smaller number of users) than a larger one. Last winter, my wife and I stayed in a hotel that had hot water on demand and it was terrible. There was about 60 seconds of hot water and that was it. On the other hand, a friend has it in her two bedroom townhouse and it suits her fine.

[phil]

electric baseboards are quick if you want heat recovery. at our summer place we used oil but we didn't want to rely on it since we often go up and just want to heat the place for the weekend. Its not the most efficient overall so far as BTU's are concerned. one factor though for a place that is often vacant is that we do pay a minimum charge so if it isn't used that often we pay for some power ( the minimum basic charge) every month whether we use it or not.

radiators and a boiler , or things like floor heating sound nice if you are home on a constant basis they do keep the temperature consistent

one thing with the electric baseboards, they are quiet, simple reliable and cheap to install so they might be good for a backup system. if my heater fails , first thing Ill do is plug in some portables , that would keep the pipes from freezing.

the radiators are attractive and neat in old houses. mine is forced air though and I dont really want to give up the space for them. I sometimes see them for free and I'm attracted until I think of where Id actually install them. I'd keep them if they already existed.

[Manalto]

For boiler efficiency, gas and oil are usually better than electric. A good gas or oil unit will have around 84% efficiency or so. The last time I checked, average electric units were a bit lower. Some electric units will advertise 90% efficiency or better, but you'll pay dearly to run them.

Thank you. I may be "misremembering" my friend's advice to look for an electrical system. On the other hand, it wouldn't be out of character for him to recommend the most expensive system available.

I have the option of a natural gas boiler, so will look into that.

Side note: My idea to install cast iron radiators and a hot water system has met with strong reaction, positive and negative. I've been accused of both "overkill" and genius. I suspect the idea resides somewhere between the two and, of course, I hope it's a good one. However, reports of accelerated global warming saturating the airwaves these past few days have caused me to wonder.

[1918ColonialRevival]

I have the option of a natural gas boiler, so will look into that.

Side note: My idea to install cast iron radiators and a hot water system has met with strong reaction, positive and negative. I've been accused of both "overkill" and genius. I suspect the idea resides somewhere between the two and, of course, I hope it's a good one. However, reports of accelerated global warming saturating the airwaves these past few days have caused me to wonder.

It's definitely not overkill, though I would recommend picking up a copy of The Ideal Fitter, which contains information on how to appropriately size radiators for rooms. The only ones saying overkill are the ones who see forced air as the only heating option out there.

I stopped believing anything I heard over the airwaves years ago. It's all about the ratings and contains little if any truth. If they are telling me to look to the Northeast, I look to the Southwest to see what's going on behind everyone's back. Seems to me I remember 30 or so years ago hearing that we were heading into an ice age after a couple of bad winters. If the Earth is really billions of years old and "official" weather records have only been kept since 1870, that's not enough data to draw any kind of a meaningful conclusion. We have miserable summers and temperate summers the same way we have rough winters and mild winters. That's about all that can be said. Climate cycles are as old as the Earth itself. The last decade the US really saw extreme weather at both ends of the spectrum was the 1930s, so it's mostly passed from living memory.