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Tankless Hot Water Heaters, Efficient, Effective, Endless.
Posts tagged solar water heater
Solar Hot Water and a Tankless
Oct 31st
To really reduce your hot water heating charges you could look at adding an active solar water heater in conjunction with a tankless water heater. The rays from the sun would pre-heat the incoming water and then the tankless would simply finish the job. It’s difficult to get a solar water heater to produce water hot enough for today’s household demands, but with the technology in a tankless system it’s a perfect fit. 
Tankless water heaters are smart no, they check incoming water temperature and vary their burners to adapt. So if you have relatively hot water coming in to a tankless it will scale down its natural gas injection to ensure that water out temperature is at your set level. If the burner is scaled down so is your gas bill as only a fraction of fuel is needed.
This is a complicated system and it will be costly, if you are doing this to save money you probably won’t see a breakeven point for a long time. If you’re interested and looking at installing a Frankenstein system you are probable doing it for the environment.
What’s required?
If your installing somewhere in the southern states this will be a lot easier as you don’t have to worry about sub-zero temperatures. Up here in Ontario it’s a definite issue and there are a few systems that can be installed. There is the Active Glycol-based system that circulates food grade glycol and transfers the heat via a heat exchanger to the potable water; this is less efficient but the safest and most popular system in Ontario. The other way is though a drain back system, potable water is forced though the solar collector and drains instantly when the water is shut off. Both these systems work to preheat a tankless systems incoming water supply ultimately reducing the heat and gas needed to raise water temperature to the desired warmth.
These dual systems are not very popular due to the increased expense but a tankless is well suited and designed for a hybrid system. If the idea seems interesting but the price too high you should note that they can be installed in stages, tankless first and then the flat plate solar collector.
Solar Water Heater and Tankless Update
Apr 21st
Solar Water Heater and Tankless
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One of our readers is working on installing a domestic solar hot water heater in conjunction with a tankless. They were going to go with a Rheem tankless to offset any additinonal temperature increase that was needed over the solar gains. Unfortunately they found out that the particular unit that they were planning on using senses the incoming water temperature, buy ‘ignores’ water that is within 40F of the target temp (ie. the unit won’t cut on to work). This has caused them some problems because:
1) The max output on any residential line is 120F (49C) (this is canadian law it cant be any hotter than this in a residential home).
2) If the solar heated water comes in at 100F (37C) or warmer, the unit will not kick on. This means the output is 37C, a cold shower to be sure.
3) If you go to the commerical unit, the max temp is 180F. This much too hot for residential use (think of someone turning on the hot water at the sink to do dishes), but it would work from the 40F differential standpoint (ie. if the water is 60C or colder, then the unit will fire, anything warmer than 60C doesn’t matter as it would be warm enough for a shower). Again this is illegal in Canada as the Max allowed Temperature is 120F.
The best solution is to more to a Rinnai Tankless water heater as this unit only requires there to be a 20 degree farenheight differentiation between water to be heated and heated water. Therfor your shower will at the very least be 100 degrees farenheight which is plenty warm enough.
These co-heating water heating systems are quite complicated so its important that you talk to a prefessional regarding any plans that you have for your home or cottage. Feel free to send us an email if you have any questions.
Solar and a Tankless
Feb 19th
Solar And A Tankless Heater
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There is starting to become a buzz around solar hot water systems. If you have a good, knowledgeable contractor a solar water system can work quite well with a tankless hot water heater. 
Here are a few of the advantages that you can expect when combining the two systems.
1. The preheated water coming from the solar water heating system will increase the flow of hot water out of a tankless unit. The reason is due to the fact the tankless has to heat pre-warmed water reducing the necessary temperature rise. The amount of hot water a tankless can provide depends on the input temperature. The greater the temperature rise necessary the slower the water can travel through the heat exchanger and the slower the output flow. Incoming water at 45F vs. 70F vs. 100F will have very different results on the output of a tankless system.
2. The water is already warm or even hot from the solar rays before entering the tankless unit and therefore the added wait time associated with a tankless unit can be reduced or even eliminated.
3. Its important when combining a tankless and solar water heater to consider a tankless unit that recognizes incoming temperature as well as outgoing and is able to fully modulate its burner (therefore only burning the necessary amount of gas to raise the temperature to the appropriate amount).
4. With the right tankless unit and an appropriately sized solar system you may find that your tankless rarely need to run. In fact some people have found that their gas bills are now costing only a few dollars as opposed to a few hundred dollars.
These Solar systems can be a little tricky in Ontario and Toronto as we have winter and the solar system (if it fails) could experience freezing. This would rupture the thermal cells in the collector rendering it ineffective. It may be necessary to use a glycol system to prevent freezing if electricity goes out. Your contractor should be able to provide all necessary info, or fill out the contact form and we can help.
