Panel radiator heating system design question (new construction house)

CalvinFish

Please – may I ask for informed feedback on the panel radiator heating plan I’ve gotten from a designer who’s experienced in radiant panels but not panel radiators? Is it a functional plan that covers all the bases, without being unnecessarily complicated & expensive?

I’m lucky to be building a new house on an small lot my family’s had for 60 years in a Massachusetts coastal community, on the southside of a hill. It’s located between ocean & bay, about 600 feet equidistant from the ocean to the east & a bay to the southwest; so winds and winter are chill - and not in the positive sense!

The builder is terrific but thinks I’m nuts for going with panel radiators when an air system would provide AC as well as heat; but – well, you guys at this site know why I want radiator heat: the comfort factor! The builder’ll provide a sub to install, but responsibility for the heat plan is on me, which is why I got a heating designer. (The only plumbers we found who were experienced in panel radiator systems were guys working the 7-digit, high end market. More power to them, but they’re out of my league).

Attached is the only schematic that the designer has provided, which shows all the equipment specified except for the radiators. Those are on floor-by-floor plans, that add just what radiators go where and placement of zone thermostats. There is nothing about the piping sequence, or TRVs, individual radiator adjustments - valves - shutoffs etc.

Also attached is a spreadsheet I made, that shows the radiators & their btu's, Manual J numbers (designer used Wrightsoft), etc. for each room/area in the 6 zones that the designer established. It’s not a homerun system b/c of affordability issues. Radiators are mostly Myson T621’s & RCV contractor series, with a few vertical Runtals sprinkled in.

I’m grateful in advance for whatever input I get. I don’t expect perfection and I’m not anal about energy efficiency (though I probably should be). But I do need a heat system that will work without continual expensive repairs/maintenance and whose components won’t die premature deaths.

njtommy

@Charlie from wmass

Rich_49

Tell him to get it all into the 130 AWT column . This chart comes from Myson engineering . At least get design temps into 150* EWT and 130* LWT

The Steam Whisperer

With a new installation using conventional zones usually doesn't make sense. It is much cheaper to install TRV's and provides much better control and lower fuel billls.

Ironman

Use a manufactured manifold like Caleffi, Rehau, etc. (no Chinese). And I second what's been said about AWT and TRV's.

CalvinFish

A couple of follow-up questions / comment, please.

Yeah, I thought a manifold would make sense. Thanks for the authoritative confirmation.

Giving every radiator a TRV sounds sweet. If done, would there be any need for zoning & a manifold? With TRV's, what would the manifold do -- just distribute the pex floor by floor (4 stories, including basement)?

Is short-cycling going to be a problem? should there be a buffer tank? The Bosch Greenstar 100 is listed with a 4.1:1 turndown ratio (max input 100,800 btu & minimum input 24,600 btu). Apart from the indirect 60 gallon domestic hot water, the existing zones' radiator btu totals are roughly:
7,000; 8,500; 8,600; 10,300 & 13,100
Though the corresponding Manual J totals are:
4,100; 6,000; 4,830; 7,900 & 8,400

I get it re: dropping the AWT. It's smart. Will have to negotiate with those who want to minimize the radiators' physical size....

Calvin

Ironman

Why are you choosing a 100k btu boiler when your load is 39k btus?

Harvey Ramer

There is no need for zoning, or a thermostat for that matter, with a PROPERLY SET UP TRV system. Everything has to be designed and commissioned correctly, and the right products have to be used. Correctly done, it is one of the most efficient systems out there.

CalvinFish

Ironman said:

Why are you choosing a 100k btu boiler when your load is 39k btus?

Yes - that's 1 of my questions, too.
The system designer said he took the 39,125 btu Manual J & added "our usual 25% safety factor". That's 48,900 btu. But after he considered the windy hillside New England coastal location, the radiators on the plan in total ended up at 60,750 btu. Then he added another 35k btu for a 60 gallon indirect water heater (Superstor SS-60). That totals 95,750 btu. Thus the 100,800 btu input boiler.

But the Superstor's 60 gallon capacity is only going to be needed in the summer, when the heat is NOT needed (the nearby beach makes it a popular destination). During heating season, there'll be just 1 or 2 people in the house; so I'm thinking that with a tank that big, its recovery time is a non-issue.

Currently spec'ed boiler is Bosch Greenstar 100: max input = 100,800 btu; DOE/gross ouput = 89,400 btu; Net IBR output = 79,000 btu.

Next size down is Greenstar 79: max input =79,200 btu; DOE/gross output = 71,000 btu; Net IBR output = 62,000 btu. Boiler's going into an otherwise unheated basement room.

??Downsize the boiler? [Rads = 60,750 btu; smaller boiler's net output = 62,000 btu]
??Exploit the oversized radiators by turning down the boiler temp?
?? Throw out the plan and find another designer? Any suggestions? It was hard to locate anyone who seemed both qualified & interested, maybe because the project's neither high end nor ultra-energy efficient.

CalvinFish

Harvey Ramer said:

There is no need for zoning, or a thermostat for that matter, with a PROPERLY SET UP TRV system. Everything has to be designed and commissioned correctly, and the right products have to be used.

Yes, to the nth degree. That's why I hired an HVAC design/consulting engineering firm with hydronics experience. And that's why I need to know whether the plan they've given me is functional & reasonable, or salvageable, or should be abandoned.

I'm up against a deadline w/the builder; but this is critical infrastructure & I don't want to screw it up.

TRV's on all radiators would be terrific. Does that involve a homerun system (a killer on installation costs bc it's a lot of time/work)? Would a semi-homerun approach work?
Manifold 1 Homerun to/from 3 Bsmt flr radiators & 5 first flr radiators
Manifold 2 Homerun to/from for 5 second floor & 5 third fr radiators
Suggestions?

I know that I don't know my armpit from my elbow on this stuff. That's why I'm here, worshipping at The Wall. Thank you all!

Ironman

Throw out your designer! He doesn't know what he's doing! Load calc programs already have about a 10 - 15% cushion built in them. And you only need the calculated btus on the coldest night of the year (design temp). That's 1% of the time. So, even a properly sized boiler is over-sized 99% of the time!

So, after coming up with 39k btus, he decided to add a "safety factor" of 25%; then he decided to add a safety factor for being on the coast of another 25%; then he added another 35k btus for the indirect?

If he used the CORRECT weather data, then NOTHING should have been added to the 39k btu number, including adding for the indirect. The indirect has priority in the programming of a mod/con boiler and space heating stops until the indirect is satisfied. Therefore, you do not add more btus for the indirect. You add more storage capacity, if needed.

Unless you have a car wash type shower, I've never seen an ordinary home that a 40 gal indirect wouldn't carry.

Because of the micro zoning, I'd recommend that you ditch the GreenStar and use a boiler with a 10 to 1 turndown like HTP's UFT 080 or Lochinvar's KHN 055.

If you need a designer, I'd highly recommend Harvey Ramer.

STEVEusaPA

Bob's last comment captures everything you need to know and do.
I also agree to contact Harvey and hopefully he has time.
I know you have a deadline, but after the builder is long gone, you'll be the one dealing with your hvac's performance, or lack of performance. And it will be much more expensive to fix it later.

Rich_49

You should easily be able to find a designer in the Coastal Mass area . Contact Emerson Swan in Randolph , maybe they can make a recommendation . Contacting another designer may be prudent , others have mentioned Harvey , and I concur . There are many designers capable of doing this properly . Find one that respects building science also to avoid future knuckleheads .

If I may make suggestions , HTP boiler (UFT 80) , Decora design panel rads w/trvs ( leverage the size to lower AWT ) , 1 circ per manifold ( yes you can use 2 manifolds) , 40 gallon indirect ( SuperStor ) w sensor , not aquastat , set temp to 150* and use a Taco 5000 series mixing valve , Taco VR 1816 or VT2218 circs , either will work although there may be some naysayers .

CalvinFish

Whew! Great advice, gents! I'm gonna follow it. I'm bummed that I made a bad decision on the heating designer, but that is what I suspected. And I'm glad to find out before it's too late and grateful for the referral.

Thank you! I'll let you know what comes of it.

hot_rod

A manifold system, even a basic copper tube type would be ideal.

With TRVs and manifold distribution, a delta P circulator in constant differential pressure mode is the best circulator control logic, or with actuators on the manifold as shown in this schematic.

Also panel rads are often designed around a 30, 35, possibly even 40°∆. Wider ∆ would assure the lowest possible return temperature. As you have noted, lowering AWT will require more panel dimension.

This Idronics has some good suggestions about zoning in general and TRV options.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_5_0.pdf

hot_rod

And if you want to mix TRVs with zones that could be controlled by a single t-stat, this is an option. Install a zone valve on the manifold with panels grouped as one zone.

Caleffi actuators can now be inverted on heating manifolds, ignore the foot note.

CalvinFish

Funny! I just finished downloading Idronics's issue 19 on Proven Hydronics Distribution Systems when I checked in here & saw Hot Rod's suggestions & referral over to another Idronics issue. They're a great resource -- though I cannot for the life of me understand it all.

I know, I know: it's not rocket science.

It's harder. But at least it's interesting.

I'll have to go get more paper & toner: at my age (which predates the digital age), if I try to absorb this stuff onscreen, it'll just go in one eye and out the other.

Thank you for the info & the manifold w/actuators pix. Very snazzy.

CalvinFish

Follow up note:
I fired the old heating designer and have ended up with a local HVAC outfit I've used before re: AC on a different house. The HVAC company's owner is working up a design with the owner of a supply house known for his hydronics savvy and then will install it.

Though not complete, here’s the big picture on the design so far:
• starting-from-scratch Manual J calculations, to size the boiler & radiators in each room/area
• Lochinvar WHN with a 10-to-1 turn down ratio
• no thermostats but TRVs on each radiator
• running the radiators at 140°F average water temp
• homerun distribution system, with each radiator piped back to a manifold
• ECM circulator pumps – either Grundfos or Taco – 1 for the manifold feeding the radiators & 1 for the indirect hot water tank (if I’m understanding it right)

I’m indebted to this site & to you all for the solid, substantive advice. Thank you!

hot_rod

That will be a sweet system, stay warm

jumper

Ironman said:

Why are you choosing a 100k btu boiler when your load is 39k btus?

I agree with all the comments here. As much as I like hydronics & dislike so many electric resistance systems; an obvious question for so little heating requirement is why not electric ceiling or high level radiant?