I have a 4 yr old boiler for my hydronic heating system which heats upstairs and downstairs, each about 1200 sq ft, and each on their own zone. We live in Seattle, WA which doesn’t get too awfully cold in the winter, except for perhaps one week a year every now and then. The boiler is rated at 120,000 BTU input and 87,000 BTU output. Since I’m needing to replace my electric water heater (60 gal) for the two-floor duplex, I’m thinking of adding a third zone for domestic hot water.
Now, I quoted the 120,000 figure to a vendor of the indirect-fired water heater equipment and he indicated that I’d have “plenty of capacity” for the third zone, but my further investigation disclosed the second figure, at about 1/3 less capacity. If I can do it, I think I’d like to get the indirect-fired water heater, but not if it is going to put my home heating at risk or run the boiler at near capacity 24/7 in the winter. If it doesn’t have the moxie, I’ll just get a gas water heater instead.
Any ideas?
Replies
Priority controls my friend. Only idiots and ignorant people size a boiler for heating + DHW load. It is a HUGE waste of money, leads to shortened equipment life, and costs lots more to operate.
I understand how priority controls would work, but how does oversizing the boiler lead to shortened equipment life?
It will short cycle leading to excessive temp. swings. Same goes for all the equipmnt involved.
WHW:
"Priority controls" Meaning size the init for heating needs, and only let the boiler heat DHW when the thermostat isn't calling for heat?
Presumably in that case, the hot water tank is sized for x days worth of hot water?
(I never see that set up in my area but am curious.)
Nope.... other way around.... when there is a DHW demand it temporarily suspens the heating until DHW demand is met. Most of the better ones will override this at some point is necessary.
I tread lightly on this subject now that Wet Head has stepped in....
I've been looking at Tekmar, Taco and Honeywell zone control panels that offer domestic hotwater priority.
We have a 50-gallon electric tank that needs to be scrapped within the next year or so, which gives me the opportunity to add a third zone for domestic hotwater and reconfigure the plumbing around the boiler to make it service friendly.
We currently have two hotwater baseboard zones.
Wet Head - could you comment on indirect tanks that work like Ergomax ?
I like the idea but haven't gained marketwide acceptance.
Makes more sense for the "dead" water to be in the tank and domestic water flow through the coils intead of the other way around.
Thanks,
Alan
And as a follow on:
I got quotes today to replace the electric WH with forced-vent gas WH: $1100 for Rheem 50 gal and $1500 for same.... Too much for me!
From my plumbing supply house:
K-Tam Jass-60 DW indirect heater, $972
Argo 4-zone controller w/priority (similar to Taco), $83.00.
The price of the K-tam was $300 less than comparable from Amtrol. These are the only two brands I've had spec'd so far, don't know what else might be available in Seattle.
Any good tips on installing a third zone to the existing 2-zone system? I know there are issues with bleeding the air from the hydronic system after putting it all together, but haven't done it before....
"There's a first time for everything"
Geoff -
We live in a 1950's ear brick ranch that was custom built (or at least it appears to be so). The heating system started out as a oil boiler supplying two baseboard zones.
Before we bought the house in 1996, it was converted to a Burnham gas boiler.
It took me two heating seasons of staring, observing, charting, and reading up on boiler piping arrangements and various ways to configure it before I was comfortable enough to tinker with the system, which, by the way, is now very stable and quiet. It is intimidating at first, but it becomes a fun puzzle that produces satisfying results.
I highly recommend you visit HeatingHelp.Com, which is run by Dan Holohan. Besides the (kindof clunky) forum "The Wall", he has several very excellent books that I urge you to purchase and study.
They are inexpensive paperbacks and entertaining.
"Pumping Away" is one of them. Other titles will be obvious to you. There is also a book on hydronic controls that is written by a woman and is perfect for the tinkering layman.
As for answering your questions, yes, a third zone can be added but obviously will involve some replumbing around the boiler.
It will be an opportunity for you to make any changes that are necessary.
Some pictures of boiler plumbing has been posted at this forum.
Many are posted at TheWall.
You may want to view some of these to get an idea what folks are doing.
As you become more familiar with what's going on, you will be able to make more sense out of what's going on in these pics, which are very inspiring. Many will show indirect tanks, etc.
Many of them look like an engine room in a yacht.
Immaculate and everything with a purpose.
I speak only as a layman who happens to be very interested in hydronics setup in a boiler room.
There are a few good ways to do this and countless ways to get it wrong. Had to make a few corrections on ours myself, and it ain't quite there yet.
Do try these books - they come highly recommended from many folks.
Alan
The "Wall" ain't clunky anymore!
re - The "Wall" ain't clunky anymore!
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Well, that just goes to show you I haven't been there lately.
I get all fired up - no pun intended - just before heating season begins.
I'm headed over there to see what changed.
Thanks !
Alan
Wet Head -
Great improvement at The Wall.
I hated how the threads kept cycling off into a black hole if I wasn't paying attention for couple days.
And I found a thread that addresses some things to consider with indirect DHW setup. May be good reading for Geoff.
http://forums.invision.net/Thread.cfm?CFID=28646&CFTOKEN=44698338&CFApp=2&Thread_ID=204&mc=12
Alan
Hey don't be scared of me. Fire away. The Ergomax type is perfect for when you need a buffer tank for your boiler... (maybe for a low mass boiler???). It's OK but hard to get in some places.
Thanks, Wet Head -
Just kidding.
I like it when you step in to thrash away at misinformation.
Ergomax, or the name itself, went through some turmoil, and I know of maybe one other brand that uses the same principal - the name escapes me but it is European. Maybe Artesian ?
Serving as a buffer is one of the advantages, and it is kindof an on-demand indirect then a storage type indirect.
Anyway, if you know of a reliable source, I would appreciate a lead.
Supply and perhaps warranty service (if ever needed) could be spotty.
Alan