Boiler size? type? In floor heat.

[bullitt94]

I know this is a frequent question.
I am in the process of building a garage. 60 x 56.
The work space will be 30 x 56 ,12 ft high,insulated. I will be using LP.
I have read older discussions about what type of boiler to use. I am thinking right now I would prefer old technology. Something that is low maintenance,even if it is less efficient,but not a lot. Unless someone convinces me different.
I have found someone selling a used Crown CXE 5.
Would this be a good choice?

 

[yeldogt]

You need a boiler protection loop to use an old style Cast iron USA type boiler for radiant ... not hard to do. But, an extra step. The german made CI boilers are designed to work with colder water. They also sit on the floor w/ open flame ..

There are small regular boilers that are somewhat simple -- may be the best route.

I get the point. For years I installed Buderus NG boilers in all my projects -- w/ indirect DHW tanks. They run forever with almost no maintenance -- what they cost in fuel is more then made up in services and parts.

You need to do a load .... a big boiler of any type will shout cycle and waste fuel

 

[Rusty Fords]

I have never installed one but have worked on a few of these on demand water heaters installed on a hydronic heating loop. Just a thought.

 

[Jackfre]

Crown make nice boilers. I am with Yeltdog in preferring Buderus. Check out the breaching for signs of condensation as well as the return section. If it was improperly piped or shows signs of any leak...run. Also, how clean is the burner compartment? Strip the jacket off and look it over. Look carefully between sections. I just looked at Crowns install manual and they list Drawing 7A for the proper by-pass method. Are you heating the whole place or only the 1500? Radiant? HydroAir? I think a 5 section a bit on the high side size wise. Being an open combustion boiler, you might consider a separate mechanical room.

 

[bullitt94]

The boiler was replaced when a gate valve was leaking above it and the owner wanted a new boiler because he was selling the property. The selling price for the boiler to me hard to beat. Thanks for telling me what to look for.
I am only heating the 1500 with radiant. The whole slab will have tubing in it. I plan on keeping the thermostat at 55 all winter and possibly adding hydo if I need fast heat. Can it be used for hot water for washing hands?
This has been in the works for a few years and I think it calculated out to 130,000 size boiler? It is finally a "go" this time.
Would it make a difference if the boiler is on the heated or unheated side? I need to know where to run the tubing.

 

[Jackfre]

You can use the boiler for hot water, but you will need an indirect, circ and controls. For simple hand washing you might be better off with a small electric tankless at the sink. Put a close eye on your expected land and decide. Placement is up to you and not having an idea of lay-out it is difficult to advise. I would suggest that you spend a little time on the Uponor and/or Rehau sites for instruction on their pex product and design.

 

[bullitt94]

Thanks Jackfre,
My mistake. What I meant was, would the boiler run more if it is on the cold side of the building?
I think it would make more sense to put the open combustion on the on the side more open to outside air.
I know where the tubing will run, I just need to decide if it will be on the heated or unheated side of the wall when the foundation gets poured.

 

[Jackfre]

I would always keep a boiler in a conditioned space. We are talking Wisconsin and the Clippers that come down your way, well, I’m sure I can’t tell you about them. Regardless of where it is located you need to provide Sufficient combustion air. Easiest on an outside wall.

 

[bullitt94]

"You need to do a load .... a big boiler of any type will shout cycle and waste fuel"
Are you saying this boiler is too big ?

 

[bullitt94]

I need a easy to use calculator to find out the correct size boiler. My notes from a couple years back might not be clear.

 

[bullitt94]

My point was,
CI boiler vs condensing boiler. Are condensing boilers worth being more efficient vs overall cost.
Also i need to know.
As far as location. I have no problem building a small room for the boiler. I just wanted to know where would be the right location. Cold side vs hot side of the garage.
I want to make sure i buy the right size boiler. I found a good price for a used cast iron boiler. But if it is too big than i will shop around for the right size.

 

[Jackfre]

A good cast iron boiler NG boiler will run in the 80+ range efficiency wise and require much less service than the wall hung. What they offer in return is higher efficiency, outdoor reset built in, modulating burners, less room, better options for venting, sealed combustion, combi (built in H and DHW) option. The world has gone wall hung and I like them, but there is still a place for a good CI boiler. I am a bit behind on the reset controls available for CI boilers so can't or won't speak to those. I would put the boiler in the conditioned space or perhaps where the two spaces join. Taht way if you choose to add heat to the adjoining space it is more convenient.

 

[bullitt94]

I think the Crown CXE 5 is 150,000 btu.
Is that too big?

 

[fitter30]

Cast boilers have to run a minimum return temp of 140*-145*. Two reasons for the temp is condensation and thermo shock. Hi efficiency condensing boilers have the advantage of running water lower temps and modulating burner ( turn down ratio). Radiate floor heat runs a water temp 5*-10*over room set point

Sent from my KFDOWI using Tapatalk

 

[bullitt94]

How do I determine the size boiler I need?

 

[yeldogt]

Find a heat load calculator .... with a well insulated shop you don't need 150k btu .... but you are only getting 120k.

I'm doing a much larger house on 65K

That's not to say it will not work .. but with propane you wan to get decent efficiencies.

How water will most likely need an indirect ......

 

[kj_mustang]

bullitt94,

Google search Loopcad. Get the free version, learn how to use it, design your floor pex loops and fill in all the design information of the building, doors, windows, insulation, etc. It will tell you the approx. btus needed.

 

[bullitt94]

Thanks.
I downloaded it. It will take a while to learn how to use it for accurate results.

 

[bullitt94]

Any opinions on Dunkirk boilers? XEB-4

 

[bullitt94]

I consider myself computer literate but loopcad is not easy to use. I cannot seem to make it so it is just a garage ,without a skylight and a number of other default items in the software that do not apply.
Not easy to trust results if I feel I cannot put in accurate information.

 

[78SC4X4]

B94. Although loopcad will show a design factor for a skylight when you create a project, it won't use it unless you insert one into your layout.

This is a good read on condensing/modulating boilers. https://www.greenbuildingadvisor.co...d energy-efficient.,-Condensing boilers wring

 

[nadogail]

Are you sure you want a boiler? Maybe a water heater will do.

Boilers make Steam, what pressure will you want to heat your garage?

 

[78SC4X4]

Are you sure you want a boiler? Maybe a water heater will do.

Boilers make Steam, what pressure will you want to heat your garage?

Some boilers make steam. Those designed for hydronic radiant heating systems do not.

 

[nadogail]

IMHO, Boilers make steam from boiling water, if the water is heated but not boiled, there will be no steam pressure and it is not a boiler; it is a water heater.

 

[shutterbugguy]

I suggest, as others mentioned, using a tankless water heater, rather than a boiler. It will be lower in cost and far more efficient. I had my new shop + house sized (6,000 SF) with a 150,000 BTU demand for radiant heat. I purchased a Takagi 177,000 BTU tankless for this. You do NOT want 140 degree water for a radiant heat system, so why heat it that high in a boiler only to need to cool it down to run through the PEX? You can search for systems like this, I've learned a lot from professionals online to help me ensure that this will work. The boiler method is the "old school" professional way to do this. The tankless heaters are not new, but are also tried and true, just haven't caught in N America until the last few years. Rheem and other also make condensing tankless heaters. These also only require PVC venting (both inlet and outlet venting) because of their efficiency, and a drain line for the condensate.

 

[bullitt94]

It seems to me that a number of people that have been in the business have said on this topic (other threads) that they do not recommend condensing boilers for radiant. Reasons for this being high maint costs and high expense to buy parts. You only have to look at #2 in this thread. I'm for long life and relatively cheap parts. Something that just runs. I don't work in the business but have been around industrial maintenance, so I know how they work and can do some maintenance. Please no lectures how I can only hire a professional to do any work on these.
I also have seen from a couple of close friends that have bought into the condensing tankless for radiant and have had them last 2 years or less. Not my idea of a good system.
Any input is appreciated.

 

[koditten]

Tankless water heaters work terrible for floor heat. I tried it. I could not get the water heater to fire because flows are way too low. Floor heat systems need the water to move slowly thru the tubes to allow the heat to transfer to the slab.

I switched to a conventional boiler (locinavar). It has a standing pilot, a relay, a thermocouple and a gas valve. Its as dumb as a stick, but anything that goes wrong can be replaced in an afternoon.

I did the math. A 96% efficient condensing boiler vs. my non condensing 80-84% efficient boiler. I figured it would take me 35 years to break even on the gas I would save going with the 96% unit.

It's no big deal to use "close spaced" loops to temper the water to the 105-115* floor systems need. It's a little more plumbing but it is still a dead reliable system.

 

[Rusty Fords]

I did the math. A 96% efficient condensing boiler vs. my non condensing 80-84% efficient boiler. I figured it would take me 35 years to break even on the gas I would save going with the 96% unit.

It's no big deal to use "close spaced" loops to temper the water to the 105-115* floor systems need. It's a little more plumbing but it is still a dead reliable system.

Return on investment (ROI) doesn't always pay to go to the higher eff stuff like some of the experts say.

The one we put in a dog kennel was just a normal gas w/h (cheap as dirt) domestic water heater with a pump to circulate the water. Not the most expensive system but worked well and cheap to install. Not a lot of stuff to break down either spend your time working on hobby not heating.

 

[stingry]

My shop is 3600 sq ft with 10 ft ceilings. It is very well insulated with R40+ ceilings and R25 walls. The slab has 2” XP’s insulation and has 12 loops of pex spaced 12” apart. Each loop is approx. 300 ft. I use a 75k btu ng power vent water heater for the hot water. I keep the thermostat set at 65 degrees all winter. The thermostat is located at eye level. I live in Western Nebraska and below zero temperatures are not uncommon. My heat load calculation called for 50 k btu at a design temp of -12 degrees. I oversized the hwt by 50% to keep the demand on the hwt to a minimum.

The heater runs very little even on the coldest days. It costs around $100 per month, gas and electricity. Very economical. Last winter was my second season and it has performed flawlessly. Not saying that there is anything wrong with boilers but seems like overkill for 1500 sq ft. Originally planned on a tankless but decided against it for several reasons, high maintenance especially considering my hard water, no warranty for diy installation, among others.

Whichever way you go, you will truly enjoy radiant floor heat, it is fantastic!!

 

[bullitt94]

I used coolcalc and came up with 45,000 BTU. I don't know if that number should be bigger for any extremes (add 50%)?
45,000 might make more sense to use a water heater. Most discussion on here seem to discourage using a water heater or it's just the ones I've found.

Loop cad is not working for me, as far as boiler size. I will probably just use it for pex layout. I'll try it again when my hair grows back a little more.