FHA to HWB conversion project

Brewbeer

Thanks again to all who have provided input, especially to hot rod who help me catch my initial undersizing errors.

I've re-calced the load analysis two ways with the BS 15% de-rating factor for baseboard output included. (Why does the industry continue to allow the baseboard manufacturers to include this BS adjustment factor in their product literature?) The first calc assumes 135 degree supply water, and the second assumes 130 degree supply water. The first includes 2 more feet of baseboard in the kitchen, and the second includes 2-4 more feet of baseboard in all the rooms except the lower level bathroom. The second scenario has about $500 more in baseboard material supplies due to an additional 2 to 4 feet of baseboard in all the rooms.

Comparison tables attached as a PDF.

Well, I have learned a lot and have a lot to think about. Thanks again for everyone's input.

--=--Ed.

Brewbeer

What is the convention when assembling long runs of baseboard? For example, an 18 foot long section, would it be OK to use 8, 8, and 2, or would a 6, 6, and 6 assembly be preferred?

Thanks.

Rich_49

I would use 3 six footers for appearances sake .

19 foot would be 2 sevens on ends and a 5 in the middle or 2 sixes with a seven in the middle . You get it .

Brewbeer

Update on my project:

The forced air system is gone, and 2 of the 3 zones of baseboards are installed and mostly piped. The question that has come up relates to circulator sizing and total head loss of each radiator and attached piping.

As a brief refresher, the new system will serve a 3 level house, each level with its own zone. The system is piped using split-loop zoning. At this point I am leaning toword using a separate circulator for each zone (vs. zone valves).

The middle zone consists of the kitchen and living room. I've calculated head loss of each radiator and attached piping. I've used the assumptions that are provided in Taco's Technical Document TD10: Selecting Circulators. Based on these calculations, the kitchen loop has a total length (including losses for fittings) of 93 feet and a head loss of 0.92 ft @ 2 gpm (3.1 ft @ 4 gpm) to the point the zone joins the main which then runs back to the boiler. The living room loop has a total length of 134 feet and a head loss of 1.33 ft @ 2 gpm (4.5 @ 4 gpm).

Can I assume that if I don't control the flow through each side of the split loop using a valve, the flow through each half of the split loop is proportional to the relative head loss of each half of the split loop?

Thank you.

SWEI

Brewbeer said:

As a brief refresher, the new system will serve a 3 level house, each level with its own zone. The system is piped using split-loop zoning. At this point I am leaning toword using a separate circulator for each zone (vs. zone valves).

I'm curious why? Your flows and head loss small and there are not currently available ECM circs here that actually fit the job. Remember that a modulating circ that runs at or near its minimum speed at design conditions won't actually modulate.

Brewbeer

I guess I haven't decided on zone valves vs. separate circulators. My last house had separate circulators for each zone.

Bob Bona_4

With those head numbers, you'd be over pumping for sure with individual circs!

Brewbeer

I'm curious about the over pumping comment.

Using the kitchen and living room zone as an example, if 4 gpm flow through each half of the split loop, the total head loss of the zone is the sum of the individual radiator losses, correct? That's 7.6 ft, and it doesn't include a flow check or any near boiler piping losses, which at a total zone flow of 8 gpm, would add another 3.5 ft of head, for a total zone head loss of approximately 11 ft. Using Taco circulators (since that's the chart I have from the TD10 technical document), the flow rate and head loss value would be above the performance curve for the 007.

What am I missing here?

Brewbeer

sorry, double post, see below

Brewbeer

So the two zones on the lower levels are done and piped back to the future boiler location and I've got one zone left (bedrooms) to install and pipe. I've read on here and other places that "bullhead" T-fittings are to be avoided, however, it would greatly simplify the piping of the zone if I could "bullhead" the return piping from the last zone, as shown on the attached diagram.

The piping for this zone is not ideal but it is this way due to access limitations from below, making it impossible to start the zone between any of the other radiators without damaging a large drywall ceiling in the family room below. Also, the zone is piped as a split loop because the total zone length would be greater than 170 feet if it were piped as a single loop.

I don't anticipate this zone will see much action since there wasn't any heat supplied to the bedrooms by the former hot air system, as the house has a rather open floor plan and the heat rises into the bedrooms without any problems. Is the bull head T on the return going to cause too many problems? Thanks.

Charlie from wmass

simple answer, yes. why the fondness for split loops? the systems originally would have used double elbows not bullhead tees in that location.

Brewbeer

The split loops provide for 130 degree supply water temps to go to each of the radiators (except the boy's and girl's bedrooms) to maximize the heat output out of each radiator while trying to limit the length of each radiator to that which fits conveniently in each room. The split loops are also piped with 1 inch back to the boiler location, to help reduce the total head of each of the zones, reducing power requirements for circulating the water in the system.

Brewbeer

Another question: how do you integrate the boiler with outdoor reset controls and variable speed pumping? It would seem to me that to maximize efficiency there needs to be a controller that is constantly analyzing outdoor temps, indoor temps, supply and return water temps, and water flow rate (e.g. how may zones are calling), and adjusting boiler firing rate and circulator pumping rate at the same time. Are boilers set up to do this, or is this really not practical?

Charlie from wmass

Yes boilers do that. Biasi Sg has a nice control. 130 seems low for our area with baseboard. I feel you are tearing down a path of over thinking this system.

Brewbeer

Charlie from wmass said:

simple answer, yes. why the fondness for split loops? the systems originally would have used double elbows not bullhead tees in that location.

This is a new install, I'm replacing a dead forced air system.

Charlie from wmass

I understand, I have followed the threads. You are worrying about minutiae. A Taco delta Temperature circulator will control even baseboard temperatures to the level of comfort beyond the average system in our fair city. A good mod con will help with the outdoor reset aspect. The issue is if you have too many balancing points you micro zone and short cycle your boiler a lot in the shoulder seasons. Occam's razor applies to heating systems.

Brewbeer

Project update: The piping is done and is holding pressure. Time to pick a boiler and the rest of the control system. I've heard good things about the Viessmann boilers, and have been looking at the Vitodens 100 (WB1B Model 26) and Vitodens 200 (B2HA Model 19). The 100 (Model 26) modulates from 34 to 83 MBH output. The 200 (Model 19) modulates from 11 to 61 MBH output.

One of the concerns expressed by the fine folks here on the wall is the low loads and small zones of my project may cause boiler short cycling. My house has a design day heat loss of 32 MBH total, with 3 zones having design day loads of 8 MBH, 12 MBH, & 12 MBH (32 ft., 48 ft., and 47 ft. of baseboard for each zone, respectively). A buffer tank has been recommended to prevent short cycling of the boiler.

Given that the Vitodens 100 lowest modulation setting (34 MBH) is greater than the design day load of my house (32 MBH), what do folks think about the Vitodens 200 with it's lowest setting (11 MBH)? Would a buffer tank still advisable/necessary/justifiable with the lower turn-down setting of the if the 200?

njtommy

The lower the firing rate the better for you.
Not sure where you did your heat loss at, but try doing one on a 50-60 degree day. That would tell you if still need a buffer tank even with 11,000 btus firing rate.

Brewbeer

Design heat loss is using a 70 degree differential (0 F).

A 50 degree day (20 degree differential) gives a total heat loss of 9,500 BTUs with individual zone losses of (2,300, 4,000 and 3,200 BTUs each.)

A 60 degree day gives a total heat loss of 5,000 BTUs (with individual zone losses of 1,100, 2,200 and 1,700 BTUs each). Typically the house temp doesn't go down if the average outdoor temp is 60 degrees (e.g. 50 at night for the low, 70 in the day for the high). Seems like electric consumption, solar gain and heat from the five of us living here probably puts out about 5,000 BTUs.

Brewbeer

Thanks for the suggestion Hatterasguy, the turn down to an 8k BTU firing rate is the lowest I've seen. Are there any other boilers that have a minimum firing rate that gets this low?

Do folks have any thought regarding the quality or the serviceability of the HTP UTF80? Any other suggestions?

Thanks again.

hot_rod

There is another 55K boiler, fire tube HX about to hit the market that turns down to 8,200 BTU/hr. It matches your system well with just about the right output on high fire. Great control also.

You will be fine with the HTP brand also.

Get as close as possible to the size you need at design.

Brewbeer

Shouldn't I be concerned about being a "guinea pig" for a new product with no prior history?

Also, any thoughts on the Lochinvar Knight WH55 ? This unit has also been suggested. It has a low firing rate of 11k BTUs, so a buffer would be needed.

Thank you for your comments.

hot_rod

A nice feature of the Lochinvar is this "ramp delay" feature. it allows you to adjust the modulation and time at each step.

So you can electronically down rate the boiler but also help program out short cycles.

With the ConXus system you can view and adjust from your phone.

https://www.youtube.com/watch?v=AwF8dONOysw

jonny88

Going to see a demo on HTP tomorrow.Every company has their guinea pigs right now.If you dont want to take a chance on technology go with an oversized cast iron boiler.Was in a house today 1800sqft and a Burnham boiler with an input of 140000k.Hit up Rich he has a lot of info on HTP.

Paul Pollets

I prefer wall panel rads to baseboard, greater output in less space, individually controllable with a TRV and they look better. They can be easily designed for 140 degree temps to match a mod-cons "sweet spot". www.heatlines.com

Brewbeer

Thanks guys.

@hot rod That ConXus looks cool. Seems like it would make programming the boiler much easier due to the use of graphical user interface. Does the add-on boiler control board have bluetooth that interfaces with a bluetooth equiped personal computer? It's not clear how you connect the boiler to the internet for remote access.

@jonny88 I don't mind taking a chance on new technology (I am looking at mod cons), I'm just not convinced that going with a unit that has no installed track record is right for me. I'd feel better about it if a couple of thousand units had been in service for a year or two so as to work out any "bugs" that might exist.

@Paul Pollets I like the look of panel rads too but I had to remove the ancient electric baseboard anyway, and a few of the rooms didn't have convenient access for running piping without disturbing a lot of finish work in the house, so that option wasn't real practical. In all honesty, I'd prefer to have radiant floors throughout, and if I ever get to do a full remodel, that's what I'll install.

Thanks again. --=--Ed.

hot_rod

Brewbeer said:

Thanks guys.

@hot rod That ConXus looks cool. Seems like it would make programming the boiler much easier due to the use of graphical user interface. Does the add-on boiler control board have bluetooth that interfaces with a bluetooth equiped personal computer? It's not clear how you connect the boiler to the internet for remote access.

@jonny88 I don't mind taking a chance on new technology (I am looking at mod cons), I'm just not convinced that going with a unit that has no installed track record is right for me. I'd feel better about it if a couple of thousand units had been in service for a year or two so as to work out any "bugs" that might exist.

@Paul Pollets I like the look of panel rads too but I had to remove the ancient electric baseboard anyway, and a few of the rooms didn't have convenient access for running piping without disturbing a lot of finish work in the house, so that option wasn't real practical. In all honesty, I'd prefer to have radiant floors throughout, and if I ever get to do a full remodel, that's what I'll install.

Thanks again. --=--Ed.

Yes you need a wifi connection, I believe it communicates to a Lochinvar server and you have a password to access the data.

Maybe Paul Rohrs will chime in, he has several systems connected.

Brewbeer

Update: My new HWB system is in and running. The installed system is the Lochinvar WHN055, Squire SIT 040 indirect, and BB30 buffer tank. System pump is the Viridian.

Some excellent discussions going on right now on the Wall. The "Taco Question" thread and the "Mod-Con Boiler and system questions???" thread are chock full of what I considered to be really meaty discussion with very relevant information. The fact that there is disagreement really makes for a great opportunity for learning and increasing understanding. The "What am I doing wrong?" thread where you guys are helping out someone set up his mod-con is also timely. Thank you.

A recap of my system: Design heat loss is 32K BTU at 0°F. 127 feet of fin tube baseboard in three zones (8K, 12K, and 12K). Emitters sized for a 130°F SWT on the design day with a delta T of 4°F, 7°F and 5°F (respectively), split loop zoning.

This morning the outdoor temp was 20°F. Boiler was on low fire (20%), 109°F boiler inlet temp, 113°F boiler outlet temp. System pump running at low speed (9W) with a similar set of numbers as the boiler. Since start up, the boiler has logged 10 space heating cycles with about 10 hours of run time.

House is evenly heated, boiler is ultra quiet (the system pump makes more noise than the boiler on low fire), and I am so glad the forced air heating system is gone!

njtommy

That's awesome news.

Brewbeer

Update ! Operating parameters just read:

20% fire
Inlet temp: 105°F
Outlet temp: 110°F
Delta T: 5°F
Flue temp: 105°F
System temp: 109°F (102°F) (middle of buffer tank)
DWH temp: 120°F (130°F) (middle of indirect tank)
ODR temp: 33°F
SH Run Hrs: 28
SH Cycles: 35
DHW Run Hrs: 6
DHW Cycles: 35

System Pump: 9 Watts
Supply Temp: 107°F
Return Temp: 102 °F

It was 20°F the past 2 nights and the system has not yet run above 20% fire while in space heating mode (at least not while I've been home), which would seem to indicate that the estimated design heat loss of 32K at 0°F (~22K at 20°F) is a significant overestimation. Seems like I need to bump the ODR curve down even more to get to constant circulation.

njtommy

That's nice big buffer tank its really going to help you.
As they say the most efficient boiler is the one that's not running.
Nice looking job.

Charlie from wmass

Thanks Tommy. I enjoyed doing it.

Brewbeer

Thank you Charlie! I very much appreciate you working with me. I'm lovin it!

And a big thank you to all the folks here on the wall who are so helpful with educating and sharing information with homeowners like myself. I probably wouldn't have designed this correctly without the help from the folks and info on this site. Definitely the best hydronic forum on the inter webs!

Charlie from wmass

You did a nice job with the baseboards. And gave me room to fit the equipment. Thanks for that.