To weld or not to weld, that is the question.
 

I'm assembling a five zone hydronic heating system and just bought all the 1.5" fittings necessary to hook it up. Not only were the parts pricey, but it will take a while to assemble them, so I was thinking maybe I should just weld up a manifold (well, two, actually, one for the supply, one for the return). It'd just be a piece of 1.5" steel pipe with holes drilled in it and 3/4" nipples welded over them. Seems easy enough and I can't see why this wouldn't work fine. I'm debating whether I should put a 1.5" to 3/4" adapter on the end of the pipe (need a shutoff valve per zone or I'd go straight to a 1.5" pump flange) or make all the zones the same and just use a cap. Can anyone think of any objections to the plan? Thanks.

Hmmm....drill and then weld, or weld and then drill? I'm leaning towards weld and then drill. Seems like it'd be harder to mess it up.

Ran the numbers and manifolds would save me 26 1.5" joints.

If you weld then drill you can leak test each nipple before drilling.

I'd be more inclined to use solder, coz I'm better at making that not leak :D

Oh, if you wanna get real fancy you can try the lab glassblowers trick, put a little air pressure in the main pipe and heat a spot with the torch, then hopefully it comes up in a bubble, you can file off the top and use it to mate the nipple in.

Have I mentioned I'm a coward? Neat idea, though.

Copper, huh? If I can get 1.5" copper pipe by the foot that might be worth looking into. I've never soldered copper together except at a standard fitting. Would that be strong enough? Drill a hole the size of the 3/4 pipe, stick it in and solder it, I guess. The system only runs at 12-15 psi or so. Food for thought.

This has me considering my own PEX manifold as well. See how this one goes.

Evidently there are PEX manifolds made in exactly this manner, so it should be strong enough. I'm pretty handy with drilling and have the equipment for holding round items (although still an amateur - EE, not ME!) so maybe I'll give it a shot for my PEX system. As far as my heating system, because I'm hanging heavy pumps off of the manifold, I think the extra strength of steel is a wise idea. Give me an excuse to practice my welding technique as well!

For PEX I think the one valve per appliance model is a bit of overkill (I have a big house so that'd mean a lot of extra PEX tubing at 20 cents a foot), but two valves per room (hot & cold) with a small manifold at each makes good sense to me and would be cheaper than having individual shutoff valves at each appliance. I like PEX over the CPVC I have been using because there are no fumes. Makes it impossible to do in winter.

OK, got it designed and bought the parts. I chose to orient the pumps in different directions since it allows them to be spaced closely but still enables them to be wired up easily. This lets me get away with the 12" 1.5 inch nipples my local store stocks (somebody stole their 1.5" die). Chose to put the fifth pump on the end since the difference in price between an end cap and the adapter wasn't much. The grey parts would be the ones welded together. I'll need to grind the 3/4" pipes to get a better fit on the 1.5" pipe for welding. I'll then drill afterward as the ability to pressure test easily is worth a lot. Good call on that, Road Warrior. :thumbup:

I know the scale is way off and I neglected the shut off valves for simplicity. Each pump will be supported on the side away from the manifold since they're rather heavy.

https://www.fuelly.com/attachments/fo...eabcd19db6.jpg

How are you controlling the pumps?

I am rolling my own circuitry, as you no doubt suspected. I hadn't really thought about it much yet. Lemme take a second....well, since there are no electric zone valves (there are check valves to keep the pumps from sucking from each other) it seems like a one relay per pump setup would do the trick.

This would be one of those times where it would be very cool to build a centrally controlled zoned system. Temperature probes in all areas going back to a digital panel that controls pumps, furnace, and even reads oil level in the storage tank and gives you a number. I'm currently working on a project that controls the AC temp and fan setting based on light levels, time of day/season, and motion. Getting it to recognize 'kyle isn't home' without being touched is turning out to be the hardest part lol.

Microcontrollers are fun!

Honeywell were having that issue a while back with their climate control systems. They had passive IR sensors to monitor rooms/zones, but if you sat real still...

I'm selling this place as soon as I'm done building it, otherwise I'd enjoy doing something more advanced.

It's just a bunch of conditions that you don't think about normally. Like, telling it that the lighting is under a certain threshold, no movement for x number of minutes, and it is after 10 assume I'm alseep and go cold doesn't work because what if I'm watching a movie? A condition then has to be written that if the lights are below a certain threshold but are not steady to say 'he's watching a movie'. Maybe I could have it post that stuff to twitter! :rolleyes:

I have, however, thought of using Zigbee wireless to allow all my DIY stuff to talk to each other so it would be able to ask if the AV reciever is on and get a yes or no back. No assumptions.

If you're selling the house... forget my DIY damper idea lol

I have a motion sensing lighting algorithm that uses two modes, one for short stays (passing through or popping in to get something) and one for longer stays. It's a learning system, so I just use two sets of variables, one for each scenario. If it fails by turning off the light too soon or you've just been in the room for a fair bit it goes into the long term mode. I tested it in a simulator I wrote and it works quite well. Writing the simulator was surprisingly hard as I realized I had no idea what my moving around behaviours actually were. Used a non-uniform random number generator with a bell curve distribution for the time between motions (I'd written it for another project).

Decided to do the return manifold first, since screw-ups will be less noticeable on it. Drilling the pipe after welding is impractical, owing to the small size of my drill press. The good news is the 3/4" nipple is quite a bit larger than 3/4" inside, so I can center it over a 3/4" hole pretty easily. Just grinding a flat the width of my grinding wheel allows the nipple half to be clamped to the 1.5" pipe in my vise with no trouble and welding it was straightforward, though it took two passes to get it leak free. Leak testing will be harder with the holes all drilled (doing them before any nipples are attached is easiest for me), but what can you do?

hot glue into the drilled holes could plug them enough to do your leak testing and should be easily removable if you don't over do it.

I have some 3/4" threaded caps already so I'm just going to weld all the nipples on and test them all at once. I also have two 1.5" to 3/4" adapters (one for each manifold) so I can do the same trick on both pipe ends. Should get the job done. Thanks, though. It only needs to be tested to about 20 psi, so that'd probably have worked fine.

Wait a second! I have some washer hoses I used to have my air handler attached with. Since there are four nipples I can hook them together in pairs to seal 'em. No pipe dope or teflon tape needed. Nice. :D

Got the return manifold done. My pressure testing setup is rather amusing looking but works fine. I noticed that each successive weld was less leaky, but only the last one was airtight right off the bat. In future, I should practice welding on some scrap before diving in if it's been a while since I've welded.

https://www.fuelly.com/attachments/fo...284ed96760.jpg

To correct the nipple alignment problems I had with the return manifold (where it doesn't really matter) when making the supply one (where it does), I drilled the holes before any welding, made a paper template of the curved ends the nipples should have to improve grinding, and made a piece of dowel on my lathe to align the nipples. Had to wrap the ends of it with masking tape as the hole diameter is slightly smaller than the nipple inside diameter. If I'd thought of it I guess I could've left one end the larger size and only wrapped one side. Rats. I only tacked them in place before removing the dowel so it wouldn't catch on fire. They came out nice and straight. Just need to pressure test and this project is done. I'm resisting the urge to redo the return one.