Caleffi manifolds EDIT: When you don't know what you don't know :)

skyking1

I don't like roof penetrations when I can avoid them, so that fan will be high in the rake wall and is there mostly for show. The window below it is an awning that will remain slightly open most of the time. I have that setup at the current home and it keeps the fresh air passing through our bathroom and out.

The ceilings are vaulted with Ijoists, no attic space. I am dropping the lid in that shower to flat at about 9.5'. The top of wall and beam are 12'. It seems a bit much in that shower.

skyking1

@Kaos

"Where are you getting 20 btu/sqft"

My heat load calcs are under 14, but the 15-20 is a littler farther down in your post.

"One way around it is to only heat high traffic areas so these can now run closer to max temp and only run the rest in the deep freeze."

I tossed the higher number in there to represent what would happen to get the floors a little more perceptibly warm. I have to look at that flow number.

"I use a plug in corded pump and a switched outlet. Turn it on in the winter, off in the summer. Pump runs 24/7 during heating season."

I really like that idea, thank you.

"Make sure the secondary is not over pumped, this is why you need to figure out actual flow rates you need. For best efficiency, the secondary flow rate has to be bellow the primary off your heat pump."

That will be helpful to consider with the pump sizing. The manual has 9-11 GPM on the performance figures for the primary. I'll go to the high side of that, and then work on keeping the secondary <10 GPM.

"No zone control can work as long as the house loads track through the day. If you have any room with large west or south facing windows, you will probably want TRVs or zone valves on those to avoid overheating."

Thanks. I have 3 rooms in mind that I would want to zone valve. I have few big windows but they do get hit with a lot of south. I can dog off the heat with window coverings in the cooling season but hate to turn away the sun all the time.

The rest of it I do intend to run free with the ODR. I'm sold that tweaking SWT and constant operation is the ticket. On that note, 0.3 GPM is only 1ft/ sec in 3/8" PEX. I was aiming for 0.5 based on maintaining velocity closer to 2 ft/sec. Am I all wet there, worrying about velocity?

hot_rod

With the newer ECM, like the Grundfos Alpha 15-58 you want to just leave it powered up as it will exercise throughout the off season. This keeps the pump from sticking. Although with attention paid to cleaning and installing good fluids.

I've started adding these Dernord sight glasses to all my systems to keep an eye on the fluid, watch for air bubbles, etc. Find them on Amazon. I buy longer glass tube from various suppliers. Here is my boiler and HP fluid observation glass.

Room by room heat loads are helpful for the loop design and flowrates. A manifold with flowmeters and actuators gives you the best control and adjustability.

Rooms with a lot of passive gain are always a challenge, especially with a high mass slab. With constant circ and some controls you can push that gain around the home to rooms that are not getting the passive gains.

At some point, adjustable window shades are the best option. You can get motorized shades now. Pella and others offer windows with shades between the glass panes. You want to deal with that passive gain durning the cooling season also.

skyking1

Thanks for that grundfos part number Bob. I was flailing around looking at all the different units.

I dove into the document and it looks like the KISS is run the constant pressure mode and let the ODR take care of the end results. Turn off a zone or two and it stays even.

I think I will plan on all remote manifolds. That closet I pictured way up thread? Up at the top of it I will have that second floor manifold and shortest possible return runs for consistency.

Down at the middle of it I will run the manifold for the East end of the main floor. It will be above the loops for optimum fill and bleed at deployment.

Service both of those manifolds with 3/4 PEX.

I figured out a great place for the West manifold. When I laid out the elevator pit I had a dimensional bust. To make the stairs nice we put in a 2x6 wall next to the bearing wall. This replaced one of my heat duct chases. I can cut and hack on that wall to my heart's desire. it just needs to fasten sheetrock at the end of the day.

I can place the manifold in the wall as you go down the stairs, at about eye height at the landing and a foot above the loops. Easy peasy working place, Simple metal door rocked in for access.

All of that facilitates making the loops a consistent length under 200'. I will nail down a loop count over the next few days.

I designed the house with a pair of cupolas to get south light to the north half. The south windows are fixed and will get those automated shades, because they are 13' above the floor and no getting to them.

If I can, I will make them outside the glass. That would be the bomb for rejecting maximum insolation.

The cool part is the North windows on the cupolas. They are sliders, and I will automate those too. When it gets hot they will open and draw hot air out the top by convection, and I will open north side basement windows to supply cool air in.

Run natural ventilation cooling until there is no more cool air to be had, then dog it all down tight and let the AC have it if needed.

hot_rod

The Caleffi manifolds with the indented sections for the tube to cross over, will fit in a 2X4 wall.

I have seen them installed in ceilings, between floor joists for example.