Help with system design, please

tbrooks · February 2018

Hi guys. As some of you may know I am trying for a diy radiant install. I have siggy's book and have been pouring over it, but it is so much information. I feel what could take me weeks to figure out, you guys would have a solution for in minutes. Let me say that I don't have a lot of money, but comfort is the goal and I will figure out how to pay for it one way or another, anywhere I can cut costs would be good. I am a very skilled diy guy, I am a handyman by trade, and I am taught by Google and do everything to specs/codes or better. I have a lot of plumbing experience and know that I can do the install, but no heating, radiant, or steam experience. I ended up paying for a design, which turned out to be basically just heat loss and tubing layout, and I was slightly disappointed. They did offer to help with any questions I may have, but I feel I would benefit from a wider knowledge base, and they mainly deal with slab, new construction.

So here is the design they gave me

Of course there are alot more pages, but I think that is the important parts. I should mention the document say that it is a lightweight over pour, when infact it is above floor retrofit, tubing with plywood sleepers and aluminum heat plates. Except the garage slab. I'm not sure if they may have otherwise compensated for this in the design. I can talk with them more if you guys feel this is an issue. Now that I have decided on a boiler it will be in the garage, and I will move manifold 1 in there as well.

So I have decided on the htp uft 80 as my boiler. I know I will need a buffer. Right now I think my next step is deciding on how to get my dhw from the system. I'm hoping to use my dhw as my buffer, if possible. Either through indirect or reverse indirect, I'm not sure the best route. And then of course the next decision is how to plumb it, either series or p/s, or whatever other options there are.

I sure would appreciate the help.

Thanks
Tony

tbrooks · February 2018

I guess I should also have mentioned I have a family of 5, we all take showers in the evening, so more dhw is better, but we make it work now off of a 40 gallon electric, just have to give some time between each shower

the_donut · February 2018

What’s the total heat loss? Those numbers look small to me. Also construction of house, gas (type) or oil, and region is helpful.

Zman · February 2018

If your electric has a 4500 watt coil, that would be 15,400 Btu/hr.
The HTP is going to generate 72,000 BTU/hr. If you use a 60 gallon tank you are going to be fine.

The lowest the HTP can modulate to for heating is 7,200 Btu/hr. Looking at your loads, that is going to cause short cycling. Keep in mind, those are design day loads, the typical load will be much lower.

I would suggest combining zones and/or adding a buffer tank.

tbrooks · February 2018

Total heat loss is 26mbtu, it is a small load. Electric would be better suited, but I wanna use lp, because ng isn't available, and I would like to run the system off a gen if the power is out (I had a thread on this recently). The house is all stick frame on continuos cement foundation, except the garage on slab. I completely gutted the house and changed the floor plan, so I have reframed most of the house and sealed it well. I'm in the southern NC mtns.

Yes zman, I understand my low load issue. I am hoping to find a way to combine dhw with my buffer so I don't need 2 tanks in the garage, along with everything else. I have read as well about communicating thermostats and zone controllers to help with the short cycling, although I haven't looked into it much yet.

I have aggressive zoning for multiple reasons. I have 2 kids that are only with me for half the winter, I have insulated their interior walls so that I don't have to have them fully heated when they are with their mom. Also the Mrs is very sensitive to temp fluctuations, so I'm trying to make sure she is happy, after all comfort is the main goal. Honestly I don't see where I could combine zones and still get the desired comfort, and I will still have small loads.

Harvey Ramer · February 2018

I would suggest using the HTP Versa-Hydro or getting a commercial water heater and building your own heating module off of the tank.
This type of equipment is perfectly suited for high DHW demand and low temp, low load space heating demand.
I have started doing this and it's so nice. Now you can zone at will with no repercussions. Plus the efficiency achieved on both space heating and DHW production is second to none!

tbrooks · February 2018

I had looked at the versa before, and also the pheonix, but between the price and the higher output, I wasn't sure it would work for my situation. Seems as though it would help simplify my system though. I will look into it more, thanks

Eastman · February 2018

What's the difference between the versa and the pioneer?

tbrooks · February 2018

I forgot that a few years ago I had posted about boilers when I first bought the property and was thinking about radiant. I went back and looked and this is what Rich said back then:

Phoenix Light Duty
http://www.htproducts.com/literature/Phoenix-LD-Brochure.pdf

FPHX for space heat . See attachment . smallest FPHX will do .

Taco 1816 on min speed for water heater side of flat plate .
http://www.taco-hvac.com/products/water_circulation_pumps__circulators/variable_speed_products/viridian_family/index.html . See instruction sheet . I'll let others recommend system side pump because we all know I'm gonna say VT2218 .

Taco 5000 mixing valve or Caleffi equivalent . For domestic .

Zone relay able to power both circs during space heating call .

Store in the heater at 160* . Mix down for the DHW , tell your wife 110* water is what she will have to live with . Everyone else should be able to shower just fine and the kid that runs it out , tell them good luck now . In summer put the thing on Eco mode , this will derate the burner by 20% . Zone the whole thing independently room by room and do not worry about the SWT because as I always say , when the surface temp reaches what it needs to be the T stat will close that zone . No more flow , no more heat .

tbrooks · February 2018

Although I think I should mix down the swt as I will have engineered wood through most of the house

Zman · February 2018

tbrooks said:
Although I think I should mix down the swt as I will have engineered wood through most of the house

Absolutely

Eastman · February 2018

Some basic stuff...

Don't use bubble wrap or bubble foil or bubble anything for insulation. The concrete in the garage needs real insulation under and around it. You would probably want to run that zone at a different temperature from the rest of the house, too.

tbrooks · February 2018

No bubbles, got it lol. I had planned on using 2" foam under slab and perimeter. I'm not really too concerned with garage "comfort", mainly that zone is to stay above freezing as it will have a mud sink, and house the heating system. I will probably keep it at around 50.

Seems that to mix down swt to my floors a 4-way motorized mixing valve with outdoor reset would be the way to go, opinions?

Rich_49 · February 2018

tbrooks said:
I forgot that a few years ago I had posted about boilers when I first bought the property and was thinking about radiant. I went back and looked and this is what Rich said back then:

Phoenix Light Duty
http://www.htproducts.com/literature/Phoenix-LD-Brochure.pdf

FPHX for space heat . See attachment . smallest FPHX will do .

Taco 1816 on min speed for water heater side of flat plate .
http://www.taco-hvac.com/products/water_circulation_pumps__circulators/variable_speed_products/viridian_family/index.html . See instruction sheet . I'll let others recommend system side pump because we all know I'm gonna say VT2218 .

Taco 5000 mixing valve or Caleffi equivalent . For domestic .

Zone relay able to power both circs during space heating call .

Store in the heater at 160* . Mix down for the DHW , tell your wife 110* water is what she will have to live with . Everyone else should be able to shower just fine and the kid that runs it out , tell them good luck now . In summer put the thing on Eco mode , this will derate the burner by 20% . Zone the whole thing independently room by room and do not worry about the SWT because as I always say , when the surface temp reaches what it needs to be the T stat will close that zone . No more flow , no more heat .

W3ew even spoke on the phone . Please realize that ODR is standard on anything I design / build .

3 way or 4 way with ODR would be appropriate . Probably 3 way and possibly as small as 1/2" due to your low loads . Don't wanna have to sift through so much water to reach goals . Bigger is not better here either .

Check out HTP Crossover Tanked unit . If not already , shortly I have been told it will be available in a 40 gallon also . Less customizable parameters than light Duty but would work fine for this application . Great price point product also .<2,000.00 .

You shoulda called me back to perform the calcs for you , these are lacking in tube size consideration and if built will have the system operating below the low end of most performance curves of circs . This is not a good thing , pump affinity laws rule here . No way around it unless you start ordering and installing more gadgets , gadgets cost money , you have a budget .

tbrooks · February 2018

Well I haven't even ordered anything yet, so it's not too late to change things. If I recall I emailed you a few times at the address you gave me, and messaged you a few times on here, but I never heard back. Plus my time table got quite delayed, had some health issues and progress was just slower than I thought, usually is remodeling by yourself. I wasn't sure if you were still willing to help, and as poor as I am, I don't like taking handouts.

I was thinking 4 way because I thought another circ would be necessary for a 3way. I will get back up with the designer and voice these concerns. They are a very nice company and have been very helpful, but I did pay them and if something is not right, it should be fixed.

tbrooks · February 2018

Well here is the response

"I don’t understand why you think you need more components than normal because of the pipe size (which I assume you mean the 1/2” PEX tube loops)? You only need a single circulator pump that will supply at least the minimum flow rate (i.e., 3.5 GPM) at the maximum head (i.e., 3.1 feet) called out in the design. Maximum pump electrical efficiency would be achieved when all loops are calling for heat by selecting a pump that places this flow rate and head at the center of the performance curve which is known as the Best Efficiency Point (BEP). Being able to provide this minimum flow rate ensures that the design delta T (i.e., the maximum difference between the supply and return temperature in each loop) will be 15F or less. Keeping the delta T to 15F or less ensures that you won’t be able to feel any floor surface temperature gradient with bare feet. If you select a pump that provides more flow rate at this head, the delta T will be even less, which is even better from a floor surface temperature gradient perspective, but does not achieve maximum pump electrical efficiency. The cheapest and smallest Taco 003 would work fine for your application. You could also select a slightly larger pump (e.g., 005 or 007) to further reduce your delta T. You could also select a more expensive smart variable speed ECM motor pump (e.g., Taco Viridian or Grundfos Alpha2) that varies the flow rate based on the actual delta T or head given the loops calling for heat that are currently active."

Rich_49 · February 2018

So what circ does he intend to use after this very well thought out response you have posted ? You do realize that the designed system will be optimal for about 10% of a heating season and possibly really suck for the remainder . It is unfortunate , but it is a fact . Systems should be designed to guarantee you'll be comfortable at or below design while being very efficient for the longest operating period , that 60 % of the season . Before contacting him again with little information about what is being told to you , let's go over it in detail

http://www.taco-hvac.com/uploads/FileLibrary/curves003-008.pdf

Harvey Ramer · February 2018

I wouldn't use anything other than a fully closed impeller on a hydronic system. The Taco 003 has a closed back and open front impeller. That style of impeller looses efficiency very quickly with a little fouling.

tbrooks · February 2018

Well hes not using anything. All they did was heat loss and tubing layout. The rest is up to me to figure out. He has been very nice and offered to help me in sizing circ, buffer, expansion, etc, but the system design from here is on me, and John's book, and hopefully you guys

I think I got what your saying though rich. The pump is just going to put out way to much flow on warmer days, especially if just one zone is calling. I have read conflicting information on high flow rates and heat transfer, I guess there are people on both sides of this argument. From either side of this argument I don't think there is any denying efficiency losses.

He did bring up another fact that I had been thinking about some. The fact that I have well water, I know most places have high iron levels in my area, at the least. Originally I was thinking I would build a purge cart and use a fluid feeder for make up water. Just thinking I may want to put the boiler on the radiant side and just have the hx to the dhw. Less components getting the well water that way. Someday I may get a good filter system, but it's not in the budget for awhile.

hot_rod · February 2018

An ECM circulator, properly set up will give you the best performance and efficiency across a wide flow range. Really no advantage to the old PSC circulators other than a few bucks.

All systems should be filled with demineralized water, most warranties insist on it.

You can filter onsite, or buy water that has been demineralized. Some wholesalers lend the demineralizer carts if you buy the resin from them.

Adding another heat exchanger will not fix the water, it just moves the problem to another commonent.

tbrooks · February 2018

I understand that on the water, just thinking that it would be better to have to replace the hx vs the boiler. I will get my water checked out and find out what is needed for a filtering system, but I just got the well drilled and it cost double what expected, plus the pump, pipe, pt, and wire I'm installing and is gonna be close to 3k so it will be a month before I can get the water running.

Rich_49 · February 2018

You were in Virginia right tBrooks ?

tbrooks · February 2018

No, southern NC mtns. Near Asheville, that's the city I found when looking for design temps

tbrooks · March 2018

Well, I've got everything coming for the well now. Hopefully gonna drop the pump in next weekend, as long as everything arrives.

So I will be hopefully pouring my garage footers the following week, and by the end of the month I will be pouring the garage slab, so if anyone thinks I should change things, let me know.

@Rich, I don't think I understand why the system won't work. I know that the system will operate below most pump curves most of the time. I have read different opinions on flow rate and heat transfer, which maybe what you are alluding too.

I know that they don't make a pump that will work extremely efficiently with my system 90% of the time, but isn't that the case with most systems? I know with ecm circulators now, the efficiency is much improved on most systems, but on my system it wouldn't do much good.

I'm sorry, I haven't had much time too look into this as I have been building a new pumphouse, getting my wiring and piping to the well installed, and working on the garage foundation. I did recall a section in John's book about micro circulators, I think they were called.

tbrooks · March 2018

As to my zoning, I guess I could combine the baths, and bring my smallest load up to ~1700btu. Put the stat in the larger bath, the door to the smaller bath will usually be open, so the extra heat would just go into the master bedroom

tbrooks · March 2018

Alright guys, garage slab is coming Monday. I never heard anything back, so I'm going with what I've got. I've made a sketch of how I think the system will be laid out in the garage, to make sure I get the manifold where I need it. Parallel direct return piping is my plan, I think this will work. Still have to pick components out, but I think I can do that later. Looked at a b&g variable pump that goes down to 5 watts, maybe a possibility.

Zman · March 2018

I think you have it all backwards. You are using a water heater as a boiler and then using a heat exchanger to make hot water? The hot water heat exchanger will never keep up using the mixed water.

Why not use the water heater to make hot water and a heat exchanger and mixing valve to do the heat.

I would suggest having someone design this for you. It wouldn't take that long and it would work...

tbrooks · March 2018

Oh your right, the mixer should be after the hx, so it will receive straight 160° water. I knew that, just in a bit of a rush to get this drawn.

I was thinking about using the hx on the floor side, but then sizing it to get the flow rates right and keeping the head loss down becomes critical.

hot_rod · March 2018

I'd use the tank for DHW and a large plate HX for the heating loads. Looks like your highest temperature on the design is 110°?

Run the tank at 130- 140, protect against DHW legionella, install a mix valve on the DHW. Then you have plenty of ∆T to supply the heating loads up to 110° via the HX. Plenty of plate HXers on e-bay at low $.

Reset the heating side if you want, but ∆T circulators don't always get along well with ODR logic.

Rich_49 · March 2018

Hot Rod said , " Reset the heating side if you want, but ∆T circulators don't always get along well with ODR logic. "

NONSENSE

Zman · March 2018

tbrooks said:
Oh your right, the mixer should be after the hx, so it will receive straight 160° water. I knew that, just in a bit of a rush to get this drawn.

I was thinking about using the hx on the floor side, but then sizing it to get the flow rates right and keeping the head loss down becomes critical.

Sizing for head loss is critical for all of this. Pay close attention to your mixing valve.
Don't design it wrong because you don't want to figure the head loss on a couple components.

HomerJSmith · March 2018

I'm not enamored with some of your bought and paid for tubing layout. I prefer to have the warmest water on the exterior walls and would have run my tubing against those walls with the cooler manifold return water toward the center of the room. I also prefer the warmest water in the garage toward the entrance where the slab isn't edge insulated and because the garage door being less insulated could allow freeze up of the pex unless you are running glycol.

leonz · March 2018

With your open floor plan the way it is why not use a steam main in the attic with steel pipe and teed to reducers for the copper in the attic using refrigerant grade soft copper pipe down feeding small surplus reclaimed steam radiators?
There are a bunch of you tube videos showing how refrigerant grade copper can feed dry steam to radiators.

if you run the steam main in the attic you set the tee's for each radiator at a 45 degree angle from horizontal to keep dry steam going to the radiators and then let the refrigerant grade soft copper piping travel along the attic trusses and then down to the specific radiator in your floor plan?

You can always install a big long radiator or two for the garage and open and close the valve(s) for the garage radiator(s) as needed.

My thoughts anyway.

tbrooks · March 2018

Hr, I was thinking with all my zoning a Delta p pump would be better suited. I'm not sure on the hx front, I was thinking that the hx would be better suited to the heating side as it would have less demand on it. Just worried about the calculations and getting the right hx.

Homer, part of that is my doing, as I requested the piping entrance locations. Because I am coming up through the subfloor, I wanted to make sure the were in places where the large notch/hole is under the least traffic. And the garage does run by the door first.

Leon, part of the reason I am doing radiant floors is to have unrestricted room. My rooms are fairly small and I don't want to worry about obstructions.

hot_rod · March 2018

Yep a ∆P cir with zone valves.
Sizing a HX with online programs. Here are some examples. A 5X12- 20 plate might be a good size. Need to know actual design loads, I assumed the tank operating 130- 140 providing radiant temperature indicated in the first design.

Zman · March 2018

hot rod said:
Yep a ∆P cir with zone valves.
Sizing a HX with online programs. Here are some examples. A 5X12- 20 plate might be a good size. Need to know actual design loads, I assumed the tank operating 130- 140 providing radiant temperature indicated in the first design.

That's the way to do it.
I would also suggest using a Taco I-series mixing valve with outdoor reset.
Whatever you use for a mixer, find one with a CV rating close to your designed flow rate.

Gordy · March 2018

HomerJSmith said:
I'm not enamored with some of your bought and paid for tubing layout. I prefer to have the warmest water on the exterior walls and would have run my tubing against those walls with the cooler manifold return water toward the center of the room. I also prefer the warmest water in the garage toward the entrance where the slab isn't edge insulated and because the garage door being less insulated could allow freeze up of the pex unless you are running glycol.

Something to think about @HomerJSmith is the type of boiler used.

If we start our loops in the middle of the room, and work coolest water to the exterior we possibly send cooler return water to the boiler room gaining some mod/con efficiency points.

Usually exterior walls are where furniture finds it’s final resting place in room layouts. Save the warmest water for where we travel.

There are special cases where tube density, and warmest water may benefit window areas of higher losses.

These are not always the cases, but something to think about in designing.

leonz · March 2018

tbrooks said:
Hr, I was thinking with all my zoning a Delta p pump would be better suited. I'm not sure on the hx front, I was thinking that the hx would be better suited to the heating side as it would have less demand on it. Just worried about the calculations and getting the right hx.

Homer, part of that is my doing, as I requested the piping entrance locations. Because I am coming up through the subfloor, I wanted to make sure the were in places where the large notch/hole is under the least traffic. And the garage does run by the door first.

=====================================================
Leon, part of the reason I am doing radiant floors is to have unrestricted room. My rooms are fairly small and I don't want to worry about obstructions.

=====================================================

About the above; A flat panel radiator is pretty slim compared to a stadard radiator and if it was one pipe steam using a header in the attic it would not take up much room to begin with as the refrigerant grade copper will not take up much space on a wall and coul be painted to match.

If there is a sub floor below the living area a steam system with panel radiators would work well too.
You need to do a lot more work before you invest in a heating system.

tbrooks · April 2018

Thanks for the insight leonz, but that won't work for me. I just don't have the room. And I've been working on the house for over 2 years, and been trying to figure out the heating for longer, although it hasn't been as serious and definite until now. Lots of people have tried to talk me into other heating methods, but I feel this is the best for my family and my situation.

Poured the garage slab today. The rest of the details on the system components will probably wait until late summer. I have to concentrate on getting everything else finished to move in in July. I shouldn't really need heat until October, and if I run the r With the hx going to the floor heat, I would need an extra circ to loop from the hx back to the htp. I'll be working on figuring this out when I have a little spare time.

Also what would be necessary to filter my well water to use to fill the system? I have yet to have it tested, but will be doing so soon, if I don't get sidetracked.

duffy_4 · April 2018

Large dwh needs small heat load highly zoned

SuperJ · April 2018

tbrooks said:

Also what would be necessary to filter my well water to use to fill the system? I have yet to have it tested, but will be doing so soon, if I don't get sidetracked.

You could get a Caleffi NA573 (and probably an extra cartridge or two). It's an inline demineralization filter system. Might be better to purchase some water for the initial fill and then use the caleffi filter for makeup.
https://www.supplyhouse.com/Caleffi-NA573022-Replenishment-Water-Treatment-Filling-Unit (this one is a full filling unit that has the pressure reduced and backflow preventer).
Or this is the filter only:
https://www.supplyhouse.com/Caleffi-NA573100-1-2-FNPT-Demineralizing-Filter-Housing-and-Color-Changing-Cartridge

Help with system design, please

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