Introduction and first question (hydronic floors)

shelton

Gordy said:

It's easier when the discussion is continued in the same thread. Then everyone can follow From the beginning.

Fair enough. What do I need to know about choosing a boiler? I presume I'll be buying the lowest-output boiler that most manufacturers offer.

Gordy

Budget of course sets the tempo.

Brand. Think of parts availability. Who will install it, and what brand they usually deal with.

Stay with a stainless steel fire tube heat exchanger.

Turn down ratio. 5:1,10:1, and 15:1

Low end modulation. Especially if zones have low loads.

some brands, and sizes to look at.

Lochinvar whn 55 has a 5:1 tdr
lochinvar khn 55. Has a 7.5:1 tdr
Heat transfer products uft 80 10:1 tdr.
HTP eft 55 5:1

Others may pipe in on other brands. That will get you started for more questions on controls etc.

Zman

billyboy said:

Copied from a post by Jason:
"Either boiler you choose needs to be sized properly. Even though I prefer mod/cons in any application I can argue the point both positive and negative on either side. I will start with the mod/con.
1. ODR is included, no extra charge. With most wireless sensor can be an option
2. Modulation, A mod/con boiler will reduce the input as needed. I have heard that a mod/con will operate in the lower half of the input 60% of the heating system
3. More important to properly size due to higher off cycle losses
4. Proper sizing gives lower turndowns for smaller zones
5. More expensive parts
6. More maintenance
7. Low return temps without worry, condensing a good thing
8. As water temperature increases takes a bigger hit on efficiency
9. Must be set up with a combustion analyzer
Outdoor air for combustion

Cast iron (ESC since OP mentioned it)
1. Need to be properly sized since
2.Full input only
3. ODR extra option
4. Can use wireless OD sensor, btw, same price as wired sensor when orderded with the ODR card, little known fact
5. less maintenace
6. Thermal mass and higher water volume a plus
7. Cannot return less than 110f, condensation bad
8. Starts with a lower efficiency but takes a smaller hit as water temperature increases.
8. Should be checked with a combustion analyzer


I will add:
Mod cons require yearly maintenance = more money
Mod cons cost MUCH more = more money
Mod cons fail more often & parts cost more = more money
Mod cons don't last as long = more money
Mod cons change design often requiring specialized technicians
that may be hard to find 10 years from now on an obsolete model, but don't worry about this as they probably won't last that long.

Who is Jason and why are you just repeating this nonsense without a little fact checking.

Just quick fact check:
Mod/cons can turn down to 10%-20%
Mod/con have higher on/off cycle losses? Not true....
Mod/cons have more expensive parts? They have more parts....
Mod/cons don't require more maintenance, they are just less forgiving when not maintained.
As temps increase,mod/cons end up with efficiencies similar to conventional boilers.
All boilers should be checked with a combustion analyzer.

My experience has been that Mod/cons only break down more often when installed incorrectly.

What you are missing here is, install the correct product for the application. The OP has a small low temp in floor system. He also has an aptitude for tech. A small mod/com boiler is perfect.

I don't know much about Jason except this post. I know that Billyboy's approach to heating is to take WAG at the heatloss and design, then run spaghetti all over the place then pat himself on the back when the house stays warm enough.

Rich_49

shelton said:

Gordy said:

With radiant floors, and your region I highly doubt return water temps will bring your efficiency of a mod/con down. They live for that type of emitter.

Sweet.

Gordy said:

Over the top is going to give the lowest water temps achievable verses under floor assemblies. Heat transfer plates also play a large role in getting those average water temps down.

I intend to go over-floor with a homemade Uponor-style Quik Trak (a buck a square for materials compared to seven for premade appeals to me). Another reason to go homemade is the option to run a larger tube. We have an open room that's going to require numerous zones as it stands to keep tube length manageable. Cement board and porcelain tile goes over that. We have a few medium-sized rugs but no carpet.

As for heat-transfer plates, is that exclusive to under-floor or do I have to run some sort of metallic conductor if I go above-floor?

Careful here . Larger tubing and shorter lengths can have even the smallest circs operating below the performance curves because of low head . This will equate to higher GPM , lower Delta t , less heat transfer , more energy used .