sizing the boiler

heatingdpeng

I am currently try to design my system, using FloPro design, it come up with heat loss is 63000 BTU on the three story house, total square foot is 5570. From theory, I should use the boiler of CGa-4 with Net AHRI 77,000. But talk to couples of plumbers, they all said due to the house is big, I should use biggest boiler, at least 50,000 more than heat loss. They suggest me to use CGa-7. I am think of using CGa-5, which NET AHRI is 102,000. Can anyone comment on this ? There is one 3x6 foot of Whirlpool in the house.
Also I draw a heating system, Can any one let me know if it is feasible ? I am using a lot of closed space Tees.

Gordy

Couple things x tank not in right location.

No circulator is drawn in the primary loop

Pipe the indirect off the primary loop.

You can cleanup the piping, and have a multi functional piece of hardware if you use a hydraulic seperator in lieu of closely spaced ts. It gives you hydraulic decoupling, dirt seperate on, air removal all in one.

What is the radiant water temp requirements for each floor? Are they different panel systems? Over the top, under floor, gypcrete? Different floor coverings? Basement pex in concrete? These may need more than one mix valve to supply different temps to different radiant panel temp requirements.

As far as boiler size, and why the other guy wants a bigger boiler. Maybe they are thinking about the indirect, and the big tub.

That is a start.

Ironman

Your heat loss numbers look low. They come out to 11.3 btu's per square foot. That would have to be an extremely tight house in a milder climate to have numbers like that.

Is this a new house? Where is it located?

As far as sizing goes, IF your numbers are correct, then that's what you should size from. What's the use in doing a load calc and then disregarding it and doubling the size of the boiler? That's real scientific and logical.

If your domestic load is unusually high, then upsize the indirect tank accordingly.

Again, check your heat loss numbers, they look low.

Rich_49

Do not be influenced into over sizing the boiler . Find someone who knows what they are doing . Hint , this someone will be willing to put in the smaller boiler . As far as the DHW consideaartion , by using a larger vessel you can use the smaller boiler , you could also use the DHW requirement as your heat loss for boiler sizing and use a smaller tank . Choice is yours , neither is wrong as long as the math is correct , again the guys you have been talking to will probably not know how to achieve this .
please provide the items asked for above , it will be easier to give you real beneficial help with that info .

Snowmelt

You don't want to go oversizing by much, have you used flow pro before, just check your numbers, no reason to oversize, these programs have the ( I will quote j.b.) have enough fudge factor to go into a diabetic coma.
May we ask where are you calling from.

SWEI

Just to add to the above: zoning with circulators in this day and age is not generally the best plan. You need a competent designer, or at least the time needed to work through this properly yourself.

Rich_49

Just looked at your picture . Couple of recommendations , some you have already heard from others . You can do this with 2 system pumps , you need some outdoor reset mixing valve/s for your radiant , make the 2nd & 3rd floors 3 loops each and keep the first floor loops at or under 200' in the panels , there is a bit of room for leader lengths . How much will the indirect , boiler and separate water heater cost you to purchase and plumb ? Please do not respond with an amount , just think about it , after thinking about it look at this , http://www.htproducts.com/versahydro.html , specifically the PHE130-55 or 80 depending on your needs , I think you'll find that this is a more affordable option that purchasing and plumbing all that other stuff . If you decide to go the route you have drawn may we strongly suggest a buffer tank sized properly to lessen if not eliminate short cycling . That's all I got for now . What say the rest of the regulars ?

Gordy

That whirlpool tub is not big......unless its 4'deep.

heatingdpeng

Thanks all the comments.
For radiant heat part, all pex is installed on top of ply wood floor, there is 1 inch foam in between
third floor,
master bathroom, 8” on center pex, fluid temp 90, max 100, 1.25gpm, floor temp is 60, tile floor
bed room. 12” center, fluid temp 90, max 100, 1.50gpm, floor temp is 60, hardwood
using Rifeng 2 branch stainless steel manifold to connect to basement, the distance is 35 feet

second floor
kitchen, 12” center, fluid temp 90, max 100, 1.25gpm, floor temp is 60, tile
living room 12” center, fluid temp 90, max 100, 1.50gpm, floor temp is 60, hardwood
using Rifeng 2 branch stainless steel manifold to connect to basement, the distance is 25 feet

basement., PEX is in the 4 inch concrete, with 2 inch R10 foam underneath
Garage 12” center, fluid temp 130, max 150, 1.25gpm, floor temp is 60, tile
Pool room, 12” center, fluid temp 130, max 150, 1.25gpm, floor temp is 60, tile
Rec room, 12” center, fluid temp 130, max 150, 2.25gpm, floor temp is 60, tile
using Rifeng 5 branch stainless steel manifold, using manual balancing valves on the manifold to adjust the flow rate on REC room

Gordy is right, I need two mixing valve, thanks for finding this my mistake

For Ironman, it is a renovated from old house, extending to the left, old section on the right using using radiator and cast iron baseboard, located in Staten island NY

For Rich McGrath, you recommend that 2nd & 3rd floors 3 loops each, what about 150’ each for 4 loops ? this way we can cut the 300 feet of my pex into half, instead of wasting 100 feet of pex..
I do some research, some highly recommend each each zone with one circular pump, some as you said, can do this with 2 systems pumps with zone valve. I think I will go for circular pump better. With your suggestion of PHE130-55/PHE199-55, so I can connect the radiant heat with this boiler, and install one Weil-Mcclain cga-5 boiler for Radiator and Cast Iron baseboard ? This way we can eliminated one mixing valve and complicated piping. We do not need indirect tank and buffer tank, do not need that water heater. The saving can buy this PHE130-55/PHE199-55. And also ore reliable. So the piping design will be like the one enclosed ? By the way, how much is this PHE130-55/PHE199-55 ?

Gordy

I think You mean floor temp 80.

What is the over the top panel methog you are using. Extruded plates I hope. Or Warmboard?


You can go shorter loops. Its all about circ sizing, and in that keeping them small to reduce power consumption. Doing 150' loops just increases the manifold size more along with costs.

Was there a heat loss calculation done room by room?

Zone valves will save you in operating costs. Does not take much juice to activate a zone valve. along with zone valves comes the need for a differental bypass, or a delta p circ.

Rich_49

PHE has a 160* capability from the space heating module . It can do the whole house as long as the EDR of rads and output of baseboard allows for that temp to be sufficient . You can eliminate a boiler , buffer tank , indirect by using this equipment . Loop length concern is to keep length in panel 200' or less . Whatever that works out to , total house we are talking 4 additional ports than what you are looking at now . The savings from possibly going on measure lower in electrical consumption should cover that , take into account the scads of cash you'll save by using one appliance instaed of a whole array of stuff I think that is really doable .
* In short , you only need the PHE and nothing else , again , as long as the 160* temp is sufficient for your rads and baseboard

heatingdpeng

Thanks Bob boan, yours instinct is right, I hand calculate my heat loss for the whole house, it come to 99905, in answering Rich, adding one port of manifold, only cost 20 dollars more, but if I cut the 300 feet of pex into 200 feet, and buy another roll of pex, cost me around 80 usd.
I do not know if this is the right argument, by using zone valves, if all the zone is always activated at the time by using one circular pump, it is a saving. But most of the time, we only activate one zone only to keep one area warmer, the rest of area is in lowest temp, so it won’t activate much, in this case, I think circulator is not much different in operating cost. I did calculate the heat loss room by room.
For with the temp only 160, I look at the chart, it is at least 25% lest BTU output, but it seem to me ok, please find enclosed my calculation

Rich_49

You are showing 160* temps for your baseboard and radiators , this is fine , if you increase them just a bit more to work with AWT 150* you do not need the Weil McLain at all . You can do this with one PHE , ALL OF IT .
* Circulators we are talking about are ECM and variable speed . So if you are only using one zone that pump may operate at 9 watts but when you open those others up the flow and head will change and the system curve will intersect the pump curve at a different point that will increase power consumption so the operating costs are kept the lowest .
* Don't cut 300 foot into 200 foot . Purchase 2 - 1000 foot coils , 1 500 foot coil and a 300 footer , you'll have 4% waste . Hopefully you added in for leader lengths and your calculations are accurate . Did you do this ?

Again , the PHE (versa hydro) can perform every heating and hot water operation here . I would lengthen the baseboard and rads to overcome the load at 150* and just use one appliance . That one appliance replaces all of the equipment you were going to purchase and costs roughly 60% less than all that nonsense not including labor and aggravation .
This unit does come equipped with an ASSE 1017 mixing valve for the domestic also , standard equipment with this unit .

Rich_49

About the price of PHE . I need to know where you are located to get an accurate idea of real cost in your location . Example , a boiler I ship to a design job in Pittsburgh costs 2,100.00 , the same boiler in my location because of metropolitan area costs 2,700.00 . Contact me through the site if you wish , I will help you facilitate purchase at the lowest cost . I will extend my pricing to you and have it shipped , you will have to contact supplier and pay for unit in advance .

bmwpowere36m3

A agree with Rich, just buy a longer coil to reduce waste. You can run shorter loops, at the expense of larger manifolds. I'm assuming your running Rifeng manifolds and Everhot PEX. I would read up on those products.


"The bitterness of poor quality remains long after the sweetness of low price is forgotten."

Benjamin Franklin

Paul48

Rich......How are they getting their efficiency? For instance, a burner input of 130k, with max. usable of 100k?

RobG

I would not use the Everhot PEX as it is type B. I would stick to a type A PEX product.

Rich_49

Paul,

The 130K is for coming out of DHW (desirable) but mostly because this unit supplies space heat by using the stored hot water in the tank , flow through the FPHX is controlled by sensors connected to S&R pipes communicating with the VS pump , hot water drawn off top and returned to bottom of tank . The usable 100K is HX penalty but since this thing won't ever shortcycle and for the heating season it will be returning fluid below 130* it will condense and when there is a hot water draw with n50* water entering tank we know it will condense . so in effect you have a unit that is capable of 10:1 turndown because of the pumping strategy of the space heating module , a unit that does not require buffering if it aggressively zoned , is a combi that actually is worth a damn , saves installation time , has outdoor reset , blah , blah , blah . You really should look at the features online . Dave has a nicely done video explaining all of it . If you're worried about OVERSIZING , don't . Better to have it and not need it than to need it and not have it . Kinda nice to have a unit that offers what this does in my opinion , but then again , I'm just one guy with an opinion . Maintenance is also kinda cool , just put purge valves on each side of flat plate at install and flush once a year and if you ever need to replace that HX for whatever reason it is an hour operation and as easy as it gets . You'll see why the main heat exchanger will never really require much if you watch the video or look at the specs . This is by far the best HX on this rock by the way . Just a company and owner who are listening and trying to make our lives and businesses easier , profitable and productive .

I think you'll see how they are getting their efficiency

Paul48

I watched the videos. It is a slick unit. The only caviat, as you said, is, you need to be sure your emitters can supply enough heat at 160* SWT. Honestly, I don't think people are cautioned enough of that, regardless of which mod/con they select. Contractors are finally understanding, to not oversize mod/cons. But they are not seeing the forest through the trees when it comes to the other end of the equation.

heatingdpeng

For Gordy question, my pex lay is Sleeper-type systems (above subfloor), for tile, I use mud job, for hardwood floor, I use 3/4 thick and 7 1/2 inch wide wood board for sleeper , leaving 3 inch in between to fill with mud, I do not use Extruded plates Or Warmboard? I do using Rifeng manifolds and Everhot PEX, unfortunately, I already bought the 300' pex, can not get 1000' now. for manifolds, any good brand to suggest ? the baseboard and radiator is a very old one, my calculation is based on new cast iron baseboard and radiator figure to figure out at 160F, the output of BTU, do not know if it is correct or not, to extend the baseboard, will be a lot work, since they are all in place, the house is in staten island NY 10304, thanks all the valuable comments

Gordy

heatingdpeng said:

For Gordy question, my pex lay is Sleeper-type systems (above subfloor), for tile, I use mud job, for hardwood floor, I use 3/4 thick and 7 1/2 inch wide wood board for sleeper , leaving 3 inch in between to fill with mud, I do not use Extruded plates Or Warmboard? I do using Rifeng manifolds and Everhot PEX, unfortunately, I already bought the 300' pex, can not get 1000' now. for manifolds, any good brand to suggest ? the baseboard and radiator is a very old one, my calculation is based on new cast iron baseboard and radiator figure to figure out at 160F, the output of BTU, do not know if it is correct or not, to extend the baseboard, will be a lot work, since they are all in place, the house is in staten island NY 10304, thanks all the valuable comments

The mud job for tile is fine, but I would use extruded plates for the hardwood. Mudding the tube in a 3" wide strip for the tubing will not spread heat very well at all. You will have stripping. Or tighten up tube centers.

Rich_49

heatingdpeng said:

For Gordy question, my pex lay is Sleeper-type systems (above subfloor), for tile, I use mud job, for hardwood floor, I use 3/4 thick and 7 1/2 inch wide wood board for sleeper , leaving 3 inch in between to fill with mud, I do not use Extruded plates Or Warmboard? I do using Rifeng manifolds and Everhot PEX, unfortunately, I already bought the 300' pex, can not get 1000' now. for manifolds, any good brand to suggest ? the baseboard and radiator is a very old one, my calculation is based on new cast iron baseboard and radiator figure to figure out at 160F, the output of BTU, do not know if it is correct or not, to extend the baseboard, will be a lot work, since they are all in place, the house is in staten island NY 10304, thanks all the valuable comments

Since you figured the cast iron at 160* there is no reason not to just use the PHE for EVERYTHING . Answer to 150' x 2 question is yes . If it works while considering leader lengths . I have a sneaking suspicion these may not have been accounted for and you'll be purchasing more pex before all is siad and done .

heatingdpeng

why consider leader lengths ?, isn't it we connect all the supply and return to manifold first, then from manifold to boiler, using a bit of bigger either 3/4 or 1" pex ?, or just use the same 1/2", if that is the case, I do not have enough,
I watch the old house episode, they discussing connect one boiler, one indirect tank, and one regular heater. when in summer, use regular heater, if not enough, will draw heat from indirect, in winter, only use indirect tank, can any one show me how to do it ?, thanks in advance

Gordy

If you can get your loops to cover, and end up at the manifold thats fine. But if you figured your tubing quanity for the floor area your screwed to get to the manifold the bigger the room, and the more remote the manifold the more your screwed.

Why add a regular water heater that makes hot water at 60% efficiency when you can have the boiler make it at 80 plus percent efficency via the indirect.....that you already have? The water heater takes up more space also.

Why not use the htp product Rich suggested, and have higher efficiency yet, and take up even less space, and save more money and the list goes on. The only disadvantge is if the unit has a seizure your out of DHW to, but then you have that with an indirect boiler set up also.

You have to watch what you take away from this old house. Just because its a TV show does not mean what they are doing is gospel......or even right for that matter.

Rich_49

I see . looking closer at your drawing you probably will not have but maybe 6 feet of leader per loop so probably not going to be an issue . 3/4" pipe will probably be quite large enough for Supply and return to manifolds granted that they are not too remote
The other thing I see is that you want multiple appliances , complicated (not really) control strategies that give you no benefit , Primary secondary piping , and to lose several square feet in the mechanical location and to spend more money than necessary while complicating your system and installation . Sorry I could not help you to do this for less and enjoy very high efficiencies .
Since you saw that on this Old House I would strongly suggest contacting Richard T for advice on his design . I would venture a guess that not many here would put together such a package . Possibly the water heater for redundancy maybe but that is alot of equipment to perform what I would consider a basic task .

heatingdpeng

thanks the comment. from third floor to basement, at least 35 feet, if put the manifold to basement, the leader will be quite long, and if three loop, will have 6 pex go from third floor to basement. So I will put it on third floor, and only need one supply and return connect the manifold to basement boiler. in this case, should I use 1/2 or 3/4 for leader ?, from second floor to basement is 25 feet. Maybe should also put the manifold to second floor too.

Gordy

You have to look at the btu needs, and flow rates for the manifold for sizing pipe to remote manifolds.

heatingdpeng

thanks, I think I will go for home run, put the manifold near the boiler, so the third floor will be 300-35-35(leader)=230 feet for one loop, I need to purchase more pex

heatingdpeng

Hi, rich, what is the cost of getting the htp product ?

Rich_49

You must contact me privately for that information . Send PM . Discussing pricing is strictly forbidden here .

bmwpowere36m3

null
You'll only get useable heat from the 230 feet (per loop), but you need to figure head loss based on 300.

heatingdpeng

appreciate if you can tell me which way better, remote manifold or home rum method

Gordy

heatingdpeng said:

appreciate if you can tell me which way better, remote manifold or home rum method

Home run Depends on how much room you have to run all the tubing from all manifolds from each floor to basement mechanical room.

Remote depends on if you have a location for manifold stations.

Either way will give the same result so long as tubing lengths for home run are reasonable. And so long s tubing diameter is ample for btu delivery in a remote manifold station.

SWEI

I prefer remote manifolds (within reason) since it eliminates the "hot spot behind the boiler room" where everything comes together.

Gordy

I agree remote installations are much cleaner.

Rich_49

Third that .

heatingdpeng

Hi, Gordy, you suggest Pipe the indirect off the primary loop, will this make the indirect higher priority ? So the hot water will go to the indirect first if it call for it. Or for other reason doing this ?

heatingdpeng

can any one help to identify which brand of pex and pex manifold is the best

SWEI

Specific brands of PEX are less important than the process used to make it. You really want PEX-a if you have a choice. It's more flexible than either PEX-b or PEX-c and can easily be repaired with a heat gun if it kinks during installation. It is sold by Uponor, Rehau, and MrPEX in this country.

Manifolds are another discussion altogether, and mostly a matter of personal preference. There have been some quality issues reported with Rifeng (a Chinese brand.)

heatingdpeng

thanks, very helpful, any body used this before ? any comment about the quality. 1/2" PE-RT plastic tubing with O2 barrier for radiant heating. It is from Oil Creek. Any experience with AquaHeat ProMix comfort pro manifold, thanks

Snowmelt

I would stick with what the guys mentioned before, what supply house are you dealing with.