Gas hot water - what system is best? Would love some advice please!

[rapunzel]

Our 'Dux' gas hot water tank went bung today. Suddenly there was all this water running onto the gas burner from the inside. I had to turn off the water supply to the heater. It is out of warranty and already a replacement of 'same' unit, less than 10 years ago. Will not get the same again.

I am thinking of a tankless gas hot water system, coupled with a solar rooftop unit. Are tankless units suited to large houses? Our home is about 45 squares and the hot water has to travel some distance to reach all the bathrooms and laundry. Unfortunately, when we shower we need to purge quite a bit of cold water before the hot comes through.

I'll start looking on Monday, but would like some input from here. What do you think are optimal solutions?

Thanks in advance.

Rapunzel

 

[hydralique]

Tankless heaters can be ganged to provide as much capacity as required - look at websites for tankless manufacturers like Noritz and Takagi. I have no idea how big "45 squares" is unless you're using roofer's teminology, in which case one square = 100 square feet.

Remember that tankless heaters can take up more space than you'd think, since you need maintenance space in front of the unit, and they also require larger gas lines. You can mount most of them outside, but they are unspeakably ugly so don't put them on a prominant exposure. If you can mount two of them, one at each end of your house, then you may eliminate some of the wait for hot water. You'll obviously have to replumb some of the house for this though.

Another solution is to intstall a circulating pump with a return line that is timed to operate when you're most likely to need hot water. That way hot water is already in the line when you turn the tap. It wastes some energy but can save a lot of water.

Besides the tank and tankless, types, there are also some hybrid models using very high capacity, computer controlled burners (like tankless units) but with small storage tanks. Usually the tank is about half the size of an equivalent conventional unit, which is possible due to the high recovery rate. They work well and are very efficient. One brand I've specified is the Polaris, made by American Water Heater. It's pricey but a 50 gallon heater will easily supply a 5000 square foot house with a family of five.

Solar systems are great and can work with either tank or tankless types.

 

[sudsmaster]

I think you need to look at why water heaters are only lasting 10 years at your home. I suspect the underlying cause is corrosive water - perhaps on the acid side, and too soft. The remedy for this is to do regular checkups on the health of the sacrificial anode rod inside the heater. Usually made out of aluminum, this rod is supposed to dissolve before the tank itself is attacked by galvanic corrosion. In corrosive water situations, the anode rod can dissolve in as little as a couple of years, instead of 20 years with non-corrosive water. When the rod goes, the tank soon follows. Replacement anode rods are not difficult to find (any plumbing supply store should have them) and as long as you have a big enough wrench, not too difficult to remove/install. In your home's case, I'd probably check the rod after the first year, and then every 2 years thereafter.

The deal with tankless water heaters is that they require more gas flow, which means a bigger gas pipe to them. They also need a bigger flue to handle the much greater combustion level. They can be noisy, so positioning them near where you want them to provide hot water in a timely manner can be a challenge.

If your water pipes are not insulated that is probably another area you should address regardless of water heater choice.

 

[brisnat81]

Hi Rapunzel

I've been researching this myself recently, with the aim of replacing our Electric Heat Exchange unit.

Edwards have a Solar tank that has an Instantaneous Gas booster. It uses a standard storage tank, but there is a gas booster on the side for when the water temp is below thermostat level. It is an all in one integrated unit.

I've been looking at the Dux Sunpro Electric with 3 collectors. It has the largest capacity of the automatic solar units 400L and will automatically control the solar pump. I know you dont want Dux, but the Dux Sunpro Gas version is a pretty well thought out piece of kit. Was your Dux unit, the one with the 5 or 10 year warranty?

Other than those two, most of the other manufactures just seem to have the standard storage tank, be it gas or electric and a manual or timer based solar control.

 

[gizmo]

Hi Rapunzel

We have solar and gas. Ours is a slightly unusual installation in that it is two separate systems, we have a valve on the wall in the loft where we select solar or gas. There are technical reasons why we had to do this. It is set up so that when we install a wood burning heater, it will also heat the water, so the gas will be just a "backup" system.

There are two or three solar hot water systems in AU I think are better, for various reasons.
1. Edwards use stainless steel tanks so less prone to corrosion than the more common glass lined steel tanks. They have been around a long time and are real experts in solar. They have a system which uses an instantaneous gas booster which only kicks in when the solar isn't hot enough. It boosts the temp of water from the solar tank if it isn't hot enough.
If there is any chance of frost at your location, you would need their system with antifreeze circulating between the tank and the solar panels which adds complication and cost. If you drink your rainwater, as we do, I would not have a system which uses antifreeze as a leak will poison your water supply.

2. Beasley (now Rinnai Beasley) are another really well established solar hot water company. They make a similar system to Edwards,including stainless steel tanks, but have a new patented frost tolerant solar panel which is guaranteed not to freeze down to about minus 10 degreesC. These are what I have and they are great. We are close to the coast so frosts are uncommon but we do get them occasionally. The other benefit of Beasley is that the gas booster they use is a Rinnai Infinity, I believe the best instantaneous gas unit on the market, and it is a special version for solar boosting which integrates better.

3. The new kid on the block is the evacuated tube type, such as Apricus or Endless Solar. The design is inherently frost safe as the water does not circulate through the evacuated glass tubes, but through an insuated manifold across the top. These can also be paired up with an instantaneous gas booster. These evacuated tube collectors work more effectively in cloudy conditions, probably not a concern in Cairns! Conversely I have read that their increased efficiency can lead to problems with them getting too hot in very hot weather, leading to the PTR valve in the tank releasing and wasting heaps of water.

There are a lot of poor installations out there which can cause grief, I'd recommend you only use a very experienced installer who specialises in solar, ie I'd search for an installer under "solar" in the yellow pages, not under "hot water".

If you want more from me, email me (email address is in my member profile), I am a member of the Alternative Technology Association and read their regular magazine "Renew", which has lots of info about the lastest in solar. Your system design will need to take account of the long pipe runs you mention, so a hot water circulating pump may be advised and these can be tricky to integrate if you have an instantaneous gas booster.

Is this for the Cairns address or Sydney?

I am on the South west Coast of Victoria where we get the highest annual rainfall in the state. If solar works here, it will work for you! And we currently have SERIOUSLY hot water.

Chris.

 

[rapunzel]

Hi everyone and thanks so much for all your advice. Now, I've looked into solar, including those stainless tanks by Edwards. I've decided against solar on the basis that it is too expensive at this point in time. Since I am on gas already and this is an established house, with solid double-brick and concrete walls, there are no rebates and too much fiddeling around, which all adds up to lots of $$$$. Considering the cost of of gas and average tank life expectancy, I would just break even by the time the next one goes bung.

Only electric water heaters come with those aluminum annodes, gas tanks don't and their life-expectancy is no more than 12 to 15 years max for the TOL models. BTW, the old Dux tank had the 5 years warranty. This is at our Sydney address and the water here is supposed to be pretty good - neither too acidic, nor alkaline. I guess this is how they play the game here.

I've put in a Rheem 185 liter tank, which apparently has a good turn-over rate and can heat double that amount of water in less than an hour. I've paid $1400 with a $100 rebate. I needed hot water quickly and, after a bit of research and talking to people in the know, I think this is the best choice for the moment.

Solar hot water systems are too costly for what they are, at this point. They are not rocket science, but fairly simple technology and materials. I ran around all weekend getting quotes. A solar system would have set me back around $6000 and I don't have that sort of money right now. I'll sit back and wait until this type of technology comes down in price. Should I ever decide to build, I'll definitely consider renewable energy. It is less costly to install new than to retro-fit.

In Cairns I live in an apartment with an off-peak electric tank in the utility room.

A big thanks again to all of you and have a great and safe holiday season.

Cheers

Rapunzel

 

[sudsmaster]

Australian water heaters must be very different from American ones, then, even the Rheems, which I thought were an American brand.

Here, both gas and electric water heaters have sacrificial anode rods. The term "anode" has nothing to do with the type of power used to heat the water. It refers to the rod acting as a sacrificial anode for galvanic corrosion. Galvanic corrosion occurs in water when two different metals are present. It's like a battery. The less noble metal dissolves into the water, protecting the more noble metal. Aluminum is less noble than steel, so it dissolves instead of the steel. Although glass lined tanks have a layer of inert porcelain protecting them from this, there is likely still some exposed steel, such as at the fittings, etc, and probably through microscopic flaws and cracks in the glazing.

If you look at the top of your gas water heater, you'll likely see a big bolt head, more than an inch diameter. That's the top of the sacrificial anode rod. Better water heaters - gas and electric - may have two such rods, with one under the bolt head, and the other incorporated into the cold water inlet. It's important to match the two - magnesium is also used as a sacrificial anode rod in some heaters. If you replace a magnesium anode rod in a dual rod heater with an aluminum one, the magnesium, being less noble than the aluminum, will quickly dissolve away, leaving you with just one rod. (Shut up Toggle ;-). There is a way to tell which type of rod your heater has. If the bolt has a large rounded bump in the middle of it, it's a magnesium rod. If the bolt has a flat top, it's an aluminum one.

Nice, eh?

 

[rapunzel]

It appears that some gas water heaters have anodes, but not all. I've just browsed the Australian Rheem website and there are a couple of models where such anodes are in the product specs. Mine has a plastic cover over the top, which looks like it isn't meant to be removed at all. There are no visible bolt heads anywhere else and I've asked the plumber about that too. He emphatically said 'no' regarding anodes in gas water heaters and explained that such come only standard with electric ones. He even mentioned the bolt heads on the top of the tanks.

I'll put a linky in for the model that I got - the Stellar. BTW, it's capacity is 160 liters, not 185, as stated earlier - sorry, my mistake.

Cheers

Rapunzel

http://www.installarheem.com.au/

 

[toggleswitch]

Ill bet that window was an expensive mistake!

Now Rich, behave yourself!

ME???? Say such a thing?
Far be it for me to have such thoughts *LOL*

........Or we will have to send you to confession to get some religion.

 

[petek]

There's no removable rod bolt on ours either though I know the one we had in Calgary did have it.
We now "rent" our gas water heater from the gas company with 24/7 service replacement if anything goes wrong with it. Off the top of my head it's something like $12 a month on the bill.

 

[sudsmaster]

Hmmm. Well, my advice, which is free and worth every penny, is that your next water heater, if it's not stainless steel, should have a sacrificial anode rod.

The water heater here is glass-lined, 30 years old, and going strong. I replaced the anode rod about four years ago; the original one was about 2/3 gone and that is generally when they should be replaced.

Here's a good discussion on anode rods. Especially the part about hidden anode rods...

http://ezinearticles.com/?How-Long-...Last?--Your-Anode-Rods-Will-Tell-Us&id=267643

 

[rapunzel]

I agree Sudsmaster. Every penny counts and some free advice can be very valuable, including yours. I appreciate your responses and have resolved to contact Rheem about this anode business. Additionally, I will try and lift the plastic cover to see what is underneath. Whilst my plumber is a relatively trustworthy and knowledgeable individual, he may not be aware of all the facts in this case, either. All shall be revealed in time.

Thanks again and happy holidays!

Rapunzel

 

[gizmo]

Where I work we have a basic Rheem internal gas hot water service.It was replaced a year or two ago. The old one had a sacrificial anode, though I have been told these are seldom replaced in AU. Most people just wait till the HWS bursts then get a new one. I am surprised to hear new ones don't always come with an anode.
At our old home in Melbourne we had a Rheem Coppermatic gas, it had a steel tank lined with copper instead of glass. They just about last for ever, we replaced it only to get an instantaneous unit, to save on space - it was a very small house. (We still have the Rheem Coppermatic on the shed here, coverted from gas to a very rough home-made solar for when we were camping here before our house was built.) Naturally as the units never wore out, the manufacturers stopped making them. (Like Belt Drive Whirlpools.)

Sudsmaster - I always thought Rheem was an Aussie company! I have just looked up their company history - they were first an American company who opened an Aussie operation in 1936. In 1973 BHP limited (a steel mining/manufacturing company) bought Rheem AU from the parent company, making Rheem AU independant from Rheem USA. They are now both owned by Paloma of Japan!

Chris.

http://www.rheem.com.au/history.asp

 

[rapunzel]

Up to now I had always connected Rheem to James Hardie Industries, for some unexplicable reason. Thanks for this info gizmo.

 

[oldhouseman]

go tankless

I installed a Rheem tankless in my house during the restoration (210 year old house) and I have no regrets. This is a gas model. I only use the gas when the water is running. I can operate the kitchen and baths without running out of hot water. The system cost me about 1400 total. My gas bill in the summer months runs about 13 to 15 dollars. My home has gas logs in the fireplaces and the gas hot water heater. The only downside was the area the plumber placed it outside. I wanted it in a more hidden spot and he was thinking water delivery. All things considered I would do this one again.

 

[rapunzel]

I briefly looked at those and it would have required a larger gas connection, which, in our case, meant greater expense and inconvenience. This was an urgent matter requiring a speedy solution.

Thanks

Rapunzel