MNBobcat said:
I'm installing an outdoor wood boiler. Inside the house I'm installing heat exchanger in my forced air furnace, a heat exchanger for domestic hot water, a heater in my garage and possibly another heater in my basement.
I'm thinking that some kind of manifold system in the house where water from the boiler is directed as each individual circuit requires heat would be the way to go. Who do you contact to design such a manifold system? I'm assuming a plumber doesn't do that kind of design and some kind of boiler expert would be whom to contact? Do I just look under boilers in the yellow pages?
There isn't all that much to designing a manifold setup, this is one of their big advantages. Essentially what you need to do is count how many loops you will be wanting and get a manifold set with at least that many outlets (it might be worth getting a couple extra and plugging them for "futureproofing" - the prices I've seen don't go up that much with number of outlets. You would then control the flow through each loop with a thermostatic valve or possibly a zone valve and some sort of thermostatic control, depending on the exact heater.
I'm not 100% sure a manifold would be the right answer for you however - it sounds like you have several different loads that each will have different BTU heating demands and require different water temperatures, which suggests that you might be better off with a series setup. A manifold delivers the same water temperature to all the loads it serves, which might not be the best thing for your setup.
Looking at your list -
1. The HVAC HX is going to be a very high BTU demand when it kicks in, which will probably be more often than many of the other loads. It will benefit from getting very hot water, and lots of it.
2. The DHW load will be lower, and more sporadic, but needs to be a priority when it hits - It also has the gotcha that since an HX works both ways, you need to make sure that it does NOT get flow if the DHW tank is hotter than the boiler supply.
3. Your garage heater will almost certainly want to be a separate loop going through a small heat exchanger so that you can run glycol in the garage part of the circuit for freeze protection. (If possible you do NOT want to run glycol in the entire system - it's expensive, and doesn't heat as well...
4. Your basement heater probably can get away with less heat than most of the other demands...
I am not an expert, so I hope HR or some of the other pros will step in if I'm to far off base, but I would think your best bet might be a series setup, with a 2 or 3-way zone valve controlling a bypass at each load to turn it on and off... Probably plumbed pretty much in the order I gave above, which would ensure that the highest demand loads would get the hottest water.
Gooserider
