Water heater - storage or tankless

[Home Improvement]

Hi all,

I'm thinking of buying a new water heater, and still confused to choose between storage water heater vs demand water heater (tankless).
Can anybody give me the pros and cons of each?
what I have so far:
1. Tankless consumes more power, and the longer you shower, the more it consumes power
2. storage has standby heat losses problem, but modern tank with better insulation should eliminate this?

initial cost is not a problem for me. my only concerns are:
1. energy cost (gas - tankless should be compared with gas - storage water heater, and electric - tankless compared only with electric - storage, no need for comparison of gas vs electric)
2. parts maintenance or durability

another topic is hazard potential between gas vs electric:
1. gas water heater has tendency to explode
2. electric water heater electrocutes?
any input on this issue?

thanks

 

[jerromyjon]

Hi and welcome! I know from experience "on-demand" water heaters are problematic and inconsistent but they should almost certainly use less energy compared to storage type water heaters, since they only heat water as you use it and it most likely takes about the same energy to heat on demand as it does to heat a tank full so you save the storage losses.
I don't know where you are but here in the U.S. there are building codes which prevent explosions and electrocutions, I can't remember ever hearing about water heater "disasters" but anything is possible...

 

[Home Improvement]

Hi and welcome! I know from experience "on-demand" water heaters are problematic and inconsistent but they should almost certainly use less energy compared to storage type water heaters, since they only heat water as you use it and it most likely takes about the same energy to heat on demand as it does to heat a tank full so you save the storage losses.
I don't know where you are but here in the U.S. there are building codes which prevent explosions and electrocutions, I can't remember ever hearing about water heater "disasters" but anything is possible...

thanks for the reply.

I'm in south east asia, and I'm installing in my own house, so, it is my responsibility to avoid all "disasters" by doing my homework and research the hazards, etc. from what you're saying about standby heat losses, it sounds like the heater is heating the water 24/7? is there a type of storage type that only heats on demand? so, it's going to be like a compact gas stove, heating water only before we take a bath. So, only when we want to take a bath:
1. draws cold water from the tap to fill the tank (10, 20 or 30L, we set the volume, so, no need to be full tank)
2. starts heating said water, where we can set the temp as we want (may take 10 - 15 minutes, just like when we manually boil the water)
3. once the desired temp is reached, we use the water
4. any leftover water stays in the tank for next use (a well insulated tank should preserve heat and therefore save energy for next heating process)
5. back to step 1

is there such a water heating system?

thanks

 

[jerromyjon]

Nothing that I've ever heard of, The only problem I can imagine with heating a tank on demand is pressure from the expanding volume of water, so you would need a temperature/pressure relief valve vented safely...

 

[tygerdawg]

Try this for real-world discussions. Is one of the best of the dozen or so plumbing forums I have found on the internet. There is sub-forum for water heaters.

https://terrylove.com/forums/index.php

My conclusions in summary based on my own investigation for my house:

• TANK: least initial cost, good flow, limited duration or volume if used for heavy consumer, requires more volumetric space for installation, significant long term usage cost, if gas-fired then works when the electricity goes off (beneficial for my family several times)
• TANKLESS: high initial cost, good flow if sized & piped properly, infinite duration, reduced long term operating costs, repairs & upgrades are expensive, small volumetric installation space, requires electricity to operate despite type of heat energy, so no hot water during power outages

The cheapest easiest solution is TANK. Because I want a new steam & luxury shower in my basement, and I'd like to provide my wife with one of those new "horse-trough" deep bathtubs upstairs for luxury soaking, will eventually go TANKLESS. Plus, I'm old enough that I can afford it.

 

[Home Improvement]

can anybody share total monthly energy consumption (KWh for electric and kilogram LPG for gas) for their water heater and how many people using water heater? a bit curious about how gas vs electric performance in terms of energy consumption.
thanks

 

[Averagesupernova]

I can tell you in a month. It happens my water heater is on a subpanel that is also submetered. There is almost nothing else that is ever using power so it would be quite accurate.

 

[jack action]

from what you're saying about standby heat losses, it sounds like the heater is heating the water 24/7? is there a type of storage type that only heats on demand? so, it's going to be like a compact gas stove, heating water only before we take a bath. So, only when we want to take a bath:
1. draws cold water from the tap to fill the tank (10, 20 or 30L, we set the volume, so, no need to be full tank)
2. starts heating said water, where we can set the temp as we want (may take 10 - 15 minutes, just like when we manually boil the water)
3. once the desired temp is reached, we use the water
4. any leftover water stays in the tank for next use (a well insulated tank should preserve heat and therefore save energy for next heating process)
5. back to step 1

is there such a water heating system?

The water heater is not heating 24/7, but the temperature is maintained at 60 °C 24/7. So the water heater is only heating a few hours a day. If you have to heat your home, the heat loss is usually not a loss as it contributes to heat your house.

My mother has done the experiment of using the water heater «as needed» to save money. It was an electric water heater and the breaker was turned off all the time except for bath time. About 20-30 minutes was needed to get the water hot enough for a bath. With 2-3 baths per week, there was enough hot water the rest of the time for doing the dishes or small tasks like that. It cut the water heater monthly consumption in half or so.

She stopped doing that when I went there once and unknowingly draw a bath of ... cold water . Not very practical to always think a half-hour ahead when you want hot water.

 

[CWatters]

Personally I like a shower to have a high flow rate. In winter it can take quite a lot of electrical power to heat water instantly/on demand. For example it might take 15kW to get a high flow rate shower. That could be 65Amps at 230V. In some places you can't draw that much current.

A tank based system can heat the water more slowly at a lower power but still deliver the high flow rate desired.