Indirect tank proximity to boiler

Zman500

I currently have a 1 year old Buderus G115 boiler with the Logamatic. My 40 gallon electric HW tank is almost dead and I'm considering replacing it with an indirect. Got a quote on a Buderus S120 tank. My current electric is next to the boiler on one side of the house with no hot water needs. I'm considering having the indirect placed 40 ft away from the boiler so it is under the kitchen and bathrooms. Any thoughts on whether this is advisable? I'd loose some efficiency from the long boiler water run, but gain from the shorter domestic water run, plus I'd get hot water faster from the faucets. Additionally, the contractor says the 32 gal S120 will provide plenty of water to replace the 40 gal electric. Do you agree? Two people live here in Maryland. Thanks.

Ironman

S120

The S120 will probably give you 3 times what the electric did. Never had a complaint from on one.



But rather than going to the expense of piping the indirect so far away, I would suggest that you look at a re-circ system for the domestic like the Grundfos "Comfort System".

lchmb

I

prefer locating the tank closer....not a fan of recirc loops.

Jean-David Beyer

My indirect is about 8 feet from my boiler.

The contractor thought nothing of this. The reason so far is there was no room closer, and that is where the old electric unit was.



When I noticed how hot the pipes were (typically 175F to and 160F from), I put 1/2 black foam insulation on those pipes. That is what I got from the local big box store. If you are going 40 feet, you might wish to go with one inch insulation instead of 1/2 inch. I believe the foam is not available in one inch, but fiberglass insulation is probably better anyway. The pipes are hot only when the heater is calling for heat, so it is not as bad as it would be were the indirect circulator running all the time.



It seems to me that doing this, especially with those pipes well insulated, would probably work out better than a recirculating system that does run (almost) all the time. But I am not a heating professional.

Ironman

Grundfos Comfort System

The Grundfos system only circulates until hot water reaches the sink where it's installed. Then the flow stops. That's the beauty of it: no wasted hot water.

Jean-David Beyer

circulates until hot water reaches the sink

1.) So does it turn on from time to time as the water near the sink cools?



2.) In my house the hot and cold water pipes are buried in the concrete slab, so there is no possibility of having a return pipe. If the Grundfos system runs the cool hot water back through the cold water supply pipe, the contamination from the hot water heater would enter the cold water pipe and I would find that unacceptable.



I happen to think burying those pipes in the slab was stupid, since the radiant heating tubing is in the slab too. In winter time, the cold water often comes out pretty warm as it gets heated by the heating system.

Zman500

Recirc Loop

Thanks for the responses.  I did not know of the Grundfos system.  I did some research and it is an interesting concept.  As Jean-David mentioned,  I also did think about the previously heated water being in my cold water pipes.  I drink the tap water directly, and when I boil food I start with cold water because I think it is cleaner, so this may be an issue.  I'll give it consideration, though.  Since the Grundfos is on a timer, what happens when the valve at the sink closes in response to the hot water reaching it, but the pump is still on because the timer hasn't timed out yet?  Wouldn't pressure build up?  Seems like the Grundfos system saves water, provides convenience, but does not save energy.  Also, considering the insane prices of oil these days, do you think it is still economical to use the indirect versus staying with electric?  Currently my boiler is off for 4 months in the summer; I'd need to leave it on.  Does the boiler need to come on even if no hot water is called for, to keep some minimum temperature in the summer? 

Jean-David Beyer

Does the boiler need to come on even if no hot water is called for, to keep some minimum temperature in the summer?

My boiler is gas fired mod-con with outdoor reset. The heat exchanger in the boiler holds only 3 quarts of water. The boiler is cold start. I am not a heating contractor, but I have read that it is not a good idea to cold start an oil burner boiler.



So I keep my boiler running all year around. I do not use a lot of hot water: no teenage daughters, for example. In the summer, the boiler comes on two or three times a day for about 10 minutes each time. Last August I used 4.17 Therms of natural gas for hot water. The minimum temperature of the boiler is the same as the outdoor temperature (boiler and indirect are in my unheated garage) -- 70F to 95F, I suppose. So my boiler does come on even though no hot water is used. Perhaps once a day for 10 minutes?

Zman

Indirect

Indirect is the right move. You will have abundant hot water at a cost of a least 1/2 of electric.

Make sure it is set up as priority over the heating load and piped so it will get the full output of the boiler without causing the boiler to condense.

I think I would install it next to the boiler. You would have to run 2- 1" lines 40' and have a floor drain at that location to move it across the house.

I am not a fan of the "comfort" circulator. I have one in my house and the cold water is always warm (were do you think the warm water from the hot water line goes).

If you have access, why not run an insulated 1/2" pex run and use a grundfos regular circulator with a timer and aquastat?

kcopp

not a fan...

of the s120. It would not meet many energy codes due to the thin insulation around it. If you opt for it still I would get a good quality insulating jacket.

billtwocase

I also

am not a fan of the 120. First and last one I installed was a joke. Needless to say, an Amtrol was sitting in it's place in no time. That was 6 years ago atleast.

Charlie from wmass

My prefered tank is the super stor

Bill you like the Amtrol? I was never a fan, might be the rocky water we have out in the Berkshires or just I get called in when they go wrong. Funny that. I have a couple s120 s out there with no problems but they are not my go to tank.

Charlie from wmass

as to the original post

tanks are kept close to the boiler because the circulation pipes for the heat side are larger then the domestic water piping and it is more cost effective to keep them short and the domestic water longer. the smaller diameter domestic water lines are easily insulated and unless the distance is very far, over 75 feet, recirculation lines tend not to be used to keep the water warm at the faucet. If the tank is piped properly and the pipe is sized properly without considering budget then you can put the tank as far away as you like from the boiler. The piping to the coil may need to be increased in size to allow for the distance and maintain the same recovery rate.

billtwocase

Charlie

Amtrol has done me good for decades. Mine is 26 years and counting in my own home. We tried them all. Each one had plus  and minuses. Our problem here is mainly the sand. Amazing how sand and rocks get in there. What is you tank of choice?  Oops, now I see your's is Super Stor.

Mac_R

S120 with Logamatic

The S120 is a really good tank.  It has a jacket loss of .24 degrees per hour.  The other good thing about it is you can use the Logamatic control to run the circulator to the indirect and keep the house and water loops separate.  Also the Logamatic 2107 has a recirculation pump control built into the control.  You don't need the Grundfoss system.  You have it with the Logamatic.  All you need to do is pipe it correctly.

Install the tank sensor that comes with the Logamatic along with its own circulator and presto.  No need for a zone control or anything.  It is all built into the Logamatic.  If you know what you are doing with that control you can make the boiler dance.  If you configure things correctly and use the Buderus mixing station you can run three different temps out of the system.  I have one that I am running a high temp loop (140-160) for some panel rads, a low temp loop (90-120) for radiant, and a ultra high temp loop (160-180) for the indirect.  System works perfectly and the customer can run two showers at the same time and not run out of hot water. 

Just a tip.  Use a mixing valve with the indirect.  I recommend a Taco 5002-C1.  Set the tank for 130 degrees to negate the chance of germs and then set the mixing valve to 120.  It is nice to be able to turn on the hot water when taking a shower and not have to touch the cold.  Also safer for kids and everyone who comes in contact with your hot water.  No more scalding hot water ever again. 

SWEI

recirc pump

Sounds lke the Logamatic can handle the controls side.  Check out the Ecorcirc e3.  Laing and B&G both sell them (using different and pointlessly confusing model numbers) but they;re great little pumps.  Under 10 Watts for most domestic recirc needs.