Electronic pilot on gas tank-type wtr htr

[patil devendra]

I have an 8 yr old AO Smith 40 gal gas hw htr. I originally had a 40 gal electric hw htr. This replacement was supposed to be cheaper than the electric unit and we were supposed to have more readily available hot water. It’s NEVER been that way. Now gas is more expensive and this unit is old and we seem to get less hot water. (already cranked upt thermostat). I’d like to replace it with a high efficiency gas unit. None of the tank types I’ve found have the efficiency of the electric units. However, the tank-types with electronic pilot seem to be just as efficient as the electrics. Questions:
1). Is there a very high efficiency gas tank-type available?
2). What are pros/cons of going to a whole-house gas tank-less unit versus gas tank-type?
3). I know this is the gas forum, but does anyone know anything about the Marathon electric wtr htr (by Rheem, I think ). http://www.marathonheaters.com/index.html If I go electric, that looks like the most efficient and longest lasting of what’s available.

TIA for your responses, a WONDERFUL site!

Paul

[SelgasParticipant]

Interesting questions you have put to the forum ptb183 and I would like to attempt to answer some of them for you.
Firstly I don’t think it matters greatly if you have requested information about electric or gas units in this forum as most of us here check out them all anyways.
I am guessing you are resident somewhere in America and that being the case may limit what is available there by comparrison to what we have down here.
Here goes anyways : I am a strong supporter of gas fired systems over electric for most domestic installations given their annual operating costs and recovery performance factors. There have been electric water heaters put into the market here that repute to have efficiencies that have never been matched before – but they do not last in the marketplace – now why would that be I wonder lol.
I do not know if Rheem manufacture for the American market a gas mains pressure water heater known down here as a “Stella” – this unit is available in two common sizes 130 and 160 litre storage with a recovery rate of 100 litres per hour. These water heaters are outdoor models and do not require the installation of a conventional flueing system as the one fitted to the water heater is vertually a “balanced flue” type. The efficiency of these heater is well up in the high 90% which is unusual for any fossil fuel burning appliance. (It is practically impossible to get any foissil fuel burning appliance to attain an efficiency of 100%).
Tankless water heaters or Instantaneous water heaters as we call them are very fast becomming the normal for most houses here as they do not require any special flueing and do not heat and store hot water. They can be made to operate with temperature control pads so the householder can select whatever temperature they require for whatever application they want hot water for.
They are available as external models and recently as an internal model, however the internal ones require a special flue which is quite expensive so they are not all that popular with customers. The efficiency of these units is high but the operating costs savings are equally impressive as they use approximately 18% less energy to attain the preset temperatures than do the most efficient gas storage heater currently available here anyways.
I can only see one draw back to these units for whole house heating ( I have one in my own home) and that is that as these unit do not “store” water but react immediatly when a faucet is opened and begin to heat water, the water is delivered internally through the machine and it slows the cooler water down in order to apply sufficient heat to obtain the preset temperature which equates to a small drop in outlet pressure to below that currently of the cold supply. This issue accepted these units would be very hard to beat on an all round basis.
As for the Marathon water heater I am unable to assist you except to say how come the others makers of such units are now no longer in the market – makes you wonder huh?
Hope all of this saga assists you to make an informed decision.

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Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

[ptb123Participant]

Thanks Peter. I live in Charleston, SC, USA. Winters sometimes in 20’s F. I had heard that point-source or tankless units have the highest efficiency ratings because some have very advanced pilot lighting systems. I ‘ m really interested in the tankless system but have heard there were problems with the fast heating of the water creating mineral deposit problems. Do you have a filter set up with your tankless unit and which brands do your recommend? This is the system I most prefer, but I don’t know of anyone in this area that uses or installs them in residential whole-house setups. I’ve seen information about Tagaki and Bosch tankless units. What’s a good warranty for these things since they are SO EXPENSIVE here compared to tank types? I don’t know who to contact in my area (tankless expertise). I have a 3 bedroom home with 2 tubs/showers, 4 hot/cold water sinks, and a washer for which we use mostly cold water. There is just my wife and me at this time but with company, possibly 4 to 6 total occupancy infrequently (holidays, vacations). Any suggestions would be appreciated. By the way, I have my 40 gallon gas unit in the corner of my garage, therefore indoors, and flued through roof already. From what I see on the internet, that would be the ideal place to install a wall-hung whole-house tankless unit. I just don’t know anyone who has used one, nor anything about how to avoid the mineral buildup problem if there is one. Sorry for the long post but you’re the first person I’ve corresponded with who has pretty much what I want. Looking forward to hearing from you!

Paul

[SelgasParticipant]

Paul
Well lets start with Brand names :
Down here we have Bosch, Rinnai, Rheem and Paloma all of which have a very good warranty system. Here they have a 100% warranty on labour and parts for first 3 years from date of installation and most have a 10 year warranty on the heat exchanger as well.
Hard water build up does not in itself apear to be a real problem to these units as I live in an area where our water supply is both very hard and aggressive. I must say I took the added protection to install a water softener to my residence and now enjoy a soft and no agressive water supply. Perhaps you should look into this issue as well.
A 24 litre unit should suffice for your requirements – these are designed to give a 25 degree C water temperature rise from the cold water inlet temperature which in our winters here is more than adequate for showers and mixing faucets.
These units will give you an endless supply of hot water provided that the gas supply and power supply to them ( to control the electronics etc ) are constantly available.
As to the pricing of these units well even down here they are a little more expensive than a storage cylinder but when you add the cost of a flue etc to a storage tank then they look a whole lot better.
The location of the unit is a matter of personal preference however, in saying that I tend to install them as close to the kitchen as is possible for that is where the most common use of short draw offs is in most homes, Showers and suchlike tend to be a longer draw off and the distance to them is not quite so important – once the hot water is there then it is there for however it is needed.
More than happy to assist you wherever I can feel free to email me if you wish.

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Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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