EFM Boiler Cold Water in Shower

leowis1 wrote: I like the hot water tank idea, but I have no idea how its going work? I must be slow. How do I hook up a pump to cycle the water from the boiler into the hot water tank? Can somebody provide me with a link to a website that shows one of these pumps? I can definitely see this as the best solution.

Hot water wants to naturally expand so you don't really need a pump.

It is true you can have an external domestic hot water storage tank without a pump, but there are trade offs. Without a pump the design criteria becomes one of optimizing the plumbing for gravity flow heat transfer from the boiler to the tank. This means the tank must close to the boiler and depending on the location of boiler supply tapings, perhaps raised. If you deplete the hot water tank, recovery time is dependent the the BTU heat transfer of the gravity plumbing. With a pump there are no such limits. The tank does not to be located next to the boiler and can be located in a more central location in the house where the distance to each facet is shorter. A pump will flow far more water than any gravity flow design so the recovery time will be a short time. The pump will only run when the hot water heater thermostat calls for heat. This is only a few minutes. The water heater thermostat can be set for whatever water temperature you desire as long as it's below the boiler water temperature. High end boiler aquastats can even overcome this limit by temporarily increasing the boiler water temperature during demand for domestic hot water. My comments apply to boilers, not necessarily to stoves with added water heating coils. Stoves may have limited domestic water production capability in which the greater flow of a pump would not be an advantage.

Yanche wrote:If you deplete the hot water tank, recovery time is dependent the the BTU heat transfer of the gravity plumbing.

The tank we have is regular electric hot water tank, so it can heat itself if need be. The cold water goes through the hot water jacket before entering the tank under any circumstances. You would have to run a full tank of hot water and deplete the boiler before you would get any unheated water in the tank.

Another benefit of this setup is you sill have hot water if you need to turn the furnace off for servicing or if something breaks.

The only problem with that setup is if the coal heated water in the tank sits in there long enough it will cool off you'll have to shower yourself with many gallons of cold water before the hot incoming water warms up the cool tank water or the hot water heater kicks on using electricity. I'm not knocking it, but I'm cheap when it comes to energy. Yes my computer and all the hookups run 24/7 no problem but I hate to run the toaster any longer than needed.

I thought of that too. I could keep the natural gas running just in case the water cools off. The t-stat on the hot water heater will heat the water only when needed.

I looked at the circulator pumps at Lowe's yesterday. $80! I'm cheap too. Is there another kind of pump I can use to do this job?

With the gravity flow circuit hooked up as shown the water in the tank will always be circulating slowly, so it won't get cold. Unless your boiler and water tank are too far apart. Thermosiphon systems are slow, like Yanche said, but they do slowly circulate. So I don't think the tank will get cold. It just may be slow to recover.

But the way Richard shows the plumbing, if you use hot water, the cold water goes through the boiler's coil, then into the water tank, so it is preheated, you should never run out of hot water.

You may find less expensive circulators on Ebay, just do a seach for 'circulator pump'. Maybe around $50 or so. But $80 isn't too bad, the current circulators with the small motor are a real bargain. The old units like the B&G red pumps were $250 or so, back when $250 might be your monthly mortgage payment!!

Did you turn off or turn down the cold water to the mixing valve?? Also did you check out the max temp that your tub/shower temp valve will allow?? I'm pretty sure you have an anti-scald max temp with thet shover valve.

Test it out for peace of mind when the young'uns are in the tub.

Greg L

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e.alleg wrote:The only problem with that setup is if the coal heated water in the tank sits in there long enough it will cool off you'll have to shower yourself with many gallons of cold water before the hot incoming water warms up the cool tank water or the hot water heater kicks on using electricity. I'm not knocking it, but I'm cheap when it comes to energy. Yes my computer and all the hookups run 24/7 no problem but I hate to run the toaster any longer than needed.

There is plenty of hot water usage in this house, it never gets cold unless you go on vacation or something and then you just flip the switch on the tank when you get back.

I like this idea more and more. Its starting to make perfect sense. I can always keep the NG pilot lit just in case I need a quicker recovery for some reason. I have to find a check valve now. Always learning something new.

I have not checked the temp valve in the shower yet. I guess it would be located in the distributer? (The handle part). I'll run over to Lowe's to pick one apart thats on the shelf and I'll look for a check valve.

I'm not burning coal yet. Still using my NG boiler. I'll switch over to coal when the highs are in the 40s. Maybe another 3-4 weeks. BTW, the guy who delivers coal to me is charging $190 per ton. Plus $10 per ton to wheel barrow it to the basement window. What do you guys pay for coal?

Take a look at the directions that came with the shower valve, if you have them... I think the lawyers have got involved [a good thing this time] and made it necessary that the temp valves cannot scald the user. The max temp should be in the directions/instructions.

Use a swinging gate one-way valve, you don't want there to be a spring in the system. The thermosiphon circulation 'pressure' is measured in fractions of an ounce.

Greg L

I checked over at Lowe's. The anti-scalf feature on my shower works only when there's a drop in water pressure. Say if somebody opens up the cold water line while you're in the shower. In the case we discussed, this won't help me.

BUT, what will work is a mixing valve when the water leaves the hot water heater. With the gravity feed system in the earlier post, it is conceivable that the water temp in the tank can reach 200 degrees. A mixing valve is the perfect remedy. Lowe's doesn't sell check valves. I have to go to a plumbing supply house. You guys have been a great help. THANK YOU!

I am thinking through the rest of my instalation and need to pickup parts for saturday , I read the posts and am confused with how to hook up hw heater??
I am planning on running boiler at 140- 160 as I have cast iron radiators, am I better off just hooking up coil with tempering valve or should I keep propane water heater and use as storage and maybe summer hot water maker..
I don't think I can raise it up very high off floor because of flue into chimney would it still circulate by itself
would I still need tempering valve after hot water heater?
do I use existing hot tapping out of top of heater to fixtures and put shuttoff on cold supply to heater when using coal boiler coil
Does any one have diagram of this setup the one in the post above doesnt show the rest of the plumbing
thanks for any help and advice

ted

Ted,
I had trouble following your post. But I am so very happy with my new setup. It works beautifully. I set my t-stat back at night and it recovers in the morning. This is when I would typically get cold showers. I'll tell you exactly how I did mine and you can do whatever you want with it.

As to the diagram, plumb the hot water from the coil into the cold water supply of the hot water heater. Plumb in a T on the cold water supply of the coil. On each side of the T you'll need to solder in check valves with the direction pointing towards the coil. Connect a hose from the bottom of your hot water heater to the one side of your T going to the cold water supply of the coil. THAT'S IT!

Don't worry about the hot water heater being physically higher than your coil. The gravity will push the water down. I have cast iron radiators and I have my aquastat set at 160-200. I put a mixing valve under the kitchen sink. I wasn't sure if this was going to work and that's why I didn't install it on the whole house hot water. But this system works great. I may move the mixing valve back into the basement to protect all the faucets from scalding water. My shower has two throttles. One for the temperature and the other for the flow of water. When the throttle is right inbetween cold and hot, its plenty hot! I have to move the throttle towards the cold side when I give the little ones a bath.

leowis1 wrote:Ted,
I had trouble following your post. But I am so very happy with my new setup. It works beautifully. I set my t-stat back at night and it recovers in the morning. This is when I would typically get cold showers. I'll tell you exactly how I did mine and you can do whatever you want with it.

As to the diagram, plumb the hot water from the coil into the cold water supply of the hot water heater. Plumb in a T on the cold water supply of the coil. On each side of the T you'll need to solder in check valves with the direction pointing towards the coil. Connect a hose from the bottom of your hot water heater to the one side of your T going to the cold water supply of the coil. THAT'S IT!

Don't worry about the hot water heater being physically higher than your coil. The gravity will push the water down. I have cast iron radiators and I have my aquastat set at 160-200. I put a mixing valve under the kitchen sink. I wasn't sure if this was going to work and that's why I didn't install it on the whole house hot water. But this system works great. I may move the mixing valve back into the basement to protect all the faucets from scalding water. My shower has two throttles. One for the temperature and the other for the flow of water. When the throttle is right inbetween cold and hot, its plenty hot! I have to move the throttle towards the cold side when I give the little ones a bath.

thanks for detiling your instalation, sounds simple and that is good at this point I think that I am in the midle of building a nuclear propulsion system and simplicity is great now.. question what type of boiler do you have and what mixing valve are you using? and what is your name leowis?
thanks ted

ted wrote: I don't think I can raise it up very high off floor because of flue into chimney would it still circulate by itself

I don't think it's necessary but it helps, if it won't circulate or circulate fast enough others have mentioned putting a small circulating pump on it.

Does any one have diagram of this setup the one in the post above doesnt show the rest of the plumbing

There's really nothing else to show. your hot water outlet from the tank doesn't have to be replumbed. Basically what you're doing is routing the cold water through the coil on the furnace before it goes into the hot water heater. The line from the drain on the bottom allows it to circulate so as the water in the tank cools it can be replaced by more hot water, this is really just a bonus. Even if you don't add that line it is still going through the hot water coil before entering the tank.

Leo,

What were the instructions that Lutz gave you?