Tankless water-heater & HVAC questions

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It's come time to upgrade the comfort and water heating systems in our new (old) house. In the interests of saving space/energy (and the fact it seems my family could drain Lake Michigan of hot water if it was what we had to use) we've decided to go with a tankless model.

For a modest sum (to say the least), our plumber has picked a Rinnai unit to install. Everything I've read has chased down most complaints to installer error rather than equipment issues. Does anyone else have any thoughts or experiences on tankless heaters? If they work out half as good as I hope, I think it will be a perfect solution for us.

On the other side of the coin, we're also looking at having a 14 SEER 2.5ton A/C unit with a 95% furnace installed around the same time. He installs Heil units - I've heard mixed results from 'net searches, but again, the general consensus is the equipment is only as good as the installer. I was going to go heat pump, but there's just too much going on this year to spend the extra money.

My only concern is he doesn't like to use a Manual J for size computing - he thinks it under-sizes the units for the area. We live in a small community - but this guy does the work for my employer, my real estate agent, and probably half the city; and hasen't let anyone down yet.

Thoughts and opnions? This is in a 1930's built story-and-a-half bungalow with ~930sqft on main and basement, with 330 sq.ft in a finished attic; all conditioned spaces.
 
When we upgraded our furnace to a Lennox G61V we noticed a significant fuel savings. We're in a rural area with propane and it's saved us about 150 gallons of propane this winter over winters with similar temperatures and the older 80% furnace. The electrical savings is also noticable. It's extremely quiet-we don't hear it at all when it runs at the lower speed.

I don't know what your temperature conditions are like, but a 14 SEER air conditioner is fairly low end. Lennox goes up to around 20 SEER. The energy savings from 14 SEER to around 20 SEER could be fairly significant.
 
This is true - 13 SEER is the least efficient they can intall legally from my understanding. But you should see my current equipment :) It's around 40+ years old. Probably 3 SEER. (Anyone's guess really). Anything they sell today would be a huge upgrade to what we have.
 
Originally Posted By: Virtuoso

My only concern is he doesn't like to use a Manual J for size computing - he thinks it under-sizes the units for the area. We live in a small community - but this guy does the work for my employer, my real estate agent, and probably half the city; and hasen't let anyone down yet.

Thoughts and opnions? This is in a 1930's built story-and-a-half bungalow with ~930sqft on main and basement, with 330 sq.ft in a finished attic; all conditioned spaces.


My reading says that the Manual J, properly used, tends to OVERsize units. "Properly used" means entering the right figures for type of insulation, window area, etc. Now, that said, if your construction type and size of home is prevalent in your city, your contractor probably knows just from experience what is going to work. The units increment by half a ton, so you can only fine tune it so much anyway.

The alleged problem with the Manual J could be from him using it incorrectly, (not being thorough), or just not wanting to spend the time. It is a plus that he at least knows what it is. However, you probably need to have a discussion with him about your preference for long run times for humidity control (assuming you have some) and even temperatures, versus any desire for quick cool down. The best humidity control, overall comfort, and cheapest operating cost come from a unit on the small end of the typical range.

Contractors often want to install larger units so that you don't call back at the height of summer because the system won't quite satisfy the thermostat (which is actually indicative of a properly sized system).
 
Just had a tankless hot water heater installed and I love it. Not only can we shower, do dishes etc. at the same time, my gas/ electric bill went down $160- in the first month. The average temp was the same, the only difference was the tankless hot water heater. Of course, I went from a 50 gallon electric and we have 8 showers a day, but the savings and convenience has been awesome.

ref
 
Old room-mate has a Bosch tankless. He likes it. I tried to convice him to just buy another tank-ed, but at the time with the tax breaks it was only another 300 bucks. It seems to me the delay is more a function of the size of the line, there doesn't seem to be any delay from the tankless. He did have to cut about a 6 x 6 inch hole in the side of his house, though.

2.5 tons sounds right. I would guess a 66,000 or the next size up for furnace, based on the little info you've given. Definitely use his judgement on this. It doesn't hurt much to be a size off on the high side, as posted earlier you can only be so close anyway. Especially if it has a dual speed or variable speed blower.
 
I did a lot of research on a/c last year and I would go with the 14 SEER. The difference in original costs (between a 14 and 18 SEER) would take many years to recoup. I'm assuming that electricity costs are far lower in NE than in NY so it would probably take even longer for you. The only justification for those super efficient units (imo) is if you live in a place where a/c is needed year round.

Also, I've read that most heating units are oversized and that a
properly sized (manual J) unit will save you money. There are free heat loss calculators on the net so you can estimate for yourself. If the installer tells you that he goes by the amount of baseboard then he is probably oversizing the unit.

PS: I believe that Heil is basically a Carrier (as is Tempstar). This is a decent unit but is not high-end. You're correct that the installation is more important.
 
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I'm continuing with a tanked heater but I installed a "tripple stage" pre-heater to warm the water before it hits the tank.

I have 2 old 1" copper baseboard pipes w/ aluminum fins and an old hw heater tank that has been stripped down to just the tank, no insulation. Wather sits in it and comes up to ambient with the baseboard radiators' fins installed before and after the pre-heater tank. I was tempted to experiment with my IR thermometer before and after, but I am happy with the results anyway. It cost nothing to install, so...

Not really a solution if you want to save space, but everyone wants to reduce the energy costs...here is a real way.
 
Originally Posted By: Audi Junkie
I'm continuing with a tanked heater but I installed a "tripple stage" pre-heater to warm the water before it hits the tank.

I have 2 old 1" copper baseboard pipes w/ aluminum fins and an old hw heater tank that has been stripped down to just the tank, no insulation. Wather sits in it and comes up to ambient with the baseboard radiators' fins installed before and after the pre-heater tank. I was tempted to experiment with my IR thermometer before and after, but I am happy with the results anyway. It cost nothing to install, so...

Not really a solution if you want to save space, but everyone wants to reduce the energy costs...here is a real way.


If your ambient temp is lower than the incoming water temp, it won't be a saving though, right?
 
I am a skeptic on tankless hot water heaters. I was looking at trying to reduce my hot water runs by moving the hot water heater from the garage to the middle of the house. ''Instant'' hot water is only at the outlet of the tank. While the units are small, the required clearances are huge. As I dug into the details, I didn't have room for one of them either near where we use hot water. I also ran their claims through my [censored] detector. I discovered their claimed savings exceeded my summer gas usage which includes a gas dryer. There is nothing that destroys my interest in any product faster than dishonest hype. If you can't make a strong enough case for your product without lying, you may keep it. I could make a rude suggestion about where. It is only fair to say, with just my wife and I in the house now, we don't use that much hot water. The honest figures for a family that uses more hot water, could be different.

You also need to look at minimum flow rates. You crank the shower to wide open hot and run it until the water get hot, then cut the volume and temperature to what you need. You step in and get soaped up, and then the unheated water hits you because the flow dropped below the minimum and it shut off. Perhaps you family need to look at some of the ways of using less hot water.

On the A/C, do you currently have one? If so, look at how well it may have done and compare its size to the new recommended one. Have you done a good job retrofitting insulation and stopping leaks? Insulation and new windows are a one time cost. Utilities go on forever and I think the only question is how fast will they go up.

What about your electrical service? If it isn't sized to handle all the new stuff, that could be another big bill. The electric tankless heaters need huge feeds.
 
From what I know the minimum flow rate and the first amount of water wasted to wait for the heat up is the biggest problem with tankless for home use. You end up wasting a lot of water if you are not using a large amount at a time (i.e washing hands, always turn off the tap when not using, etc).

One of my coworker rebuild his home 5 years ago and his calculation shows that tankless would not be a good idea for his use because of his fluctuation in water flow need. Sometimes his stay home wife would do laundry and shower at the same time. A tank could act as a buffer that works well for all kinds of workload.
 
Originally Posted By: Dan55
Consumer Reports did a test on tankless in Oct 08 an interesting read.

Here's the abbreviated version, I believe:
http://www.consumerreports.org/cro/appli...-heaters-ov.htm

To the OP - since you live in NE, your average ground water temps are relatively low. This means that you will have to find a powerful enough tankless heater that will deliver pretty high temperature rise (difference betw. incoming and outgoing water temp). A big powerful tankless obviously costs more upfront and it also costs more to operate, so you need to factor it all in when doing a comparison.

My biggest gripe with tankless heaters is the minimum water flow required to engage the heater - what others wrote already. Granted, the last one I used was about 15 years ago - technology has probably improved since.
 
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Originally Posted By: PandaBear

If your ambient temp is lower than the incoming water temp, it won't be a saving though, right?


The tank's situated next to the furnace in the basement and the finned radiators run right over the ducts.
 
I'm not sold on tankless. My gas bill with a regular water heater is only $30/month during the summer. If I saved 50% on gas that is only $180 per year. It would have cost me an additional $1,800 to install a tankless vs. a top of the line Bradford White 50 gallon tank model. So my break-even point is 10 years. What some plumbers won't tell you is the extreme heat produced by a tankless model requires calcium/hard water deposits to be flushed on a yearly basis. When that expense is factored in, I'm not sure a tankless makes sense in a retrofit situation.
 
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another issue with a tankless is parts when it has a breakdown. 1 day of cold showers makes a grouchy family. When the plumber tells you the water heater needs to be sent in to be repaired or that parts are $300 and 3 days away, the joys of endless hot water just ended. on the other hand most plumbers have parts in their van for a conventional water heater and parts are available at the local hardware store.

I would double check with your plumber that repair parts are readily available the same day in your area.
 
Originally Posted By: Brett Miller
I'm not sold on tankless. My gas bill with a regular water heater is only $30/month during the summer. If I saved 50% on gas that is only $180 per year. It would have cost me an additional $1,800 to install a tankless vs. a top of the line Bradford White 50 gallon tank model. So my break-even point is 10 years. What some plumbers won't tell you is the extreme heat produced by a tankless model requires calcium/hard water deposits to be flushed on a yearly basis. When that expense is factored in, I'm not sure a tankless makes sense in a retrofit situation.


Worse yet, halve your summer gas usage, and your bill may only go down $5. I just looked my current bill, $155 for the gas used, and $51 for service and distribution. Different companies have different ways of covering their fixed costs during periods of low usage.
 
Thanks for all the input guys!

We ended up going with the original bid of a 14 SEER 2.5 ton A/C & 95% 80k BTU furnace and Rinnai R75LSi tankless heater. So far I'm very pleased with how everything works.

The old furnace was a 120k (96k bonnet) BTU monster. I swear the heat exchangers were seriously thick..made to last for sure. But probably took forever to heat up. The A/C was an old Westinghouse unit; still cooled ok but had trouble keeping up on the hot days.

The water heater was a 19 year old 40gallon gas unit; and it sounded like popcorn when the burner was on. Sometimes it would pop hard enough to feel through the house. Average summer gas bill: $45. But space savings was also a major consideration in this purchase too, otherwise we may have simply upgraded to a 50 gallon tanked unit.


Just getting that ancient a/c out of here really made the yard look better.

ac.jpg
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Do you have an efficient boiler in the mix? Use the boiler to heat a tank and you get nearly the same efficiency as the boiler itself. These hot water tanks are incredible as losses are something like 1/4-1/2 F degree loss/hour. You also do not run out of hot water.

I run a Buderus (German top notch) oil burner at 93% efficient which is significantly better than any tankless situation running at 75% efficiency. Hot water tanks gas or electric are worse typically for efficiency.
 
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