new hot water system design

jonny23

I am a homeowner, not a pro. I need to upgrade my heating system and want to switch from an old gas fired steam system to a hot water mod-con baseboard system. I have been reading this site and trying to learn as much as I can but need some pro advice on my system design so I know what I'm talking about when interviewing contractors. I have done a heat loss myself accounting for new dense pack cellulose that will be blown in this winter. I will be putting in replacement windows this summer. My plan is to install an indirect hot water tank to the system as well. Here are my heat loss numbers:



Winter Outdoor Design Temp: 9

Winter Indoor Design Temp: 72



House heat loss approx. 30,000 btu



Zone 1 - First Floor

Living Room West - 3,646

Living Room East - 5,114

Entry Foyer & First Floor Stairway - 2,188

Dining Room - 5,187

Kitchen - 3,994



Zone 2

Bathroom - 1,105

North Bedroom - 2,893



Zone 3

Bedroom East - 1,584

Bedroom West - 3,405



What I want to know is what size should the boiler and hot water tank be?

How should I size my baseboard based on these btu numbers from the heat loss? Is there a recommended gpm and water temperature for the baseboard loops?

I am looking at Heating Edge high output baseboard with top supply bottom return. I want to design the system so it is maximizing its potential for high efficiency. I'm not totally convinced that the contractors I've spoken with so far have this in mind and don't want to spend the money for a high efficiency boiler and find out the install or system design prevents it from operating at full potential.

Paul48

Micro-zones

Four and 5000 btu zones will give you nothing but grief. Control the heat for the bedrooms with TRV's and let the mod/con handle the structure. Add 20% to the heat loss for bathrooms.

jonny23

split 2nd floor zone

I was originally thinking of splitting a single zone for the entire 2nd floor with a run from the basement for the east and west bedroom and a separate run for the north bedroom and bathroom. One plumber I spoke with said I might get problems with air trapped in the system and recommended against it. Are there major issues with doing it this way?

gennady

zoning

why do you need zoning in the first place?

jonny23

control of 2nd floor

independent control of 2nd floor and first floor temps. would you suggest something different?

gennady

control

But why would you want control over zones?

gennady

boiler

Are you installing modulating boiler or just want to upgrade heating system?

Mark N

Why?

What is wrong with the steam system, other than the boiler being old. I have a small home with a gas fired steam boiler. The temps are very even throughout the house and operating costs are low. According to my figures since installing the new boiler 4 years it has been running me approx $825 a year to heat the house. Have you considered making the steam system right before investing a lot of money in a new heating system?

Mark N

TRV's

You can install TRV's on the rads in steam system and have control over the temp in every room. The only rad that can't have a TRV is the one in the room with the Thermostat.

jonny23

steam issue

i have. several rads were pulled during renovations at some point. I just moved into the house last april. There is no steam piping or place for a radiator in the kitchen or the bathroom. In its current state it is insufficient to heat the house properly and the boiler needs replacement. If it was simply the boiler I would stick with the steam system as I love the heat the radiators put out.

jonny23

incentives

so then we get to incentives. i get rebates for the boiler and hot water tank and the price to replace the steam system then becomes close to what it would cost to just replace the steam boiler, which regardless of cost doesn't make sense as far as future comfort. see reply below.

jonny23

mod

installing mod con boiler

gennady

zoning

Then what is the reason for installing zoning?

Mark N

Steam System

It is a shame that the steam system in your house has been ruined. I can't help with mod con system as a now nothing about them.

jonny23

alternative

What is the alternative system design? I am not a professional so help me understand what you are implying.

Paul48

Zoning

Zoning was a means of controlling comfort for conventional boilers.No offense, but you are stuck in that mentality, and you have to lose that. Mod/cons work best when allowed to control the temperature of the whole structure. You are in the perfect situation, because you are installing the radiation.You can ensure the proper amount based on heat loss of each room. The 2 major problems I see here are people with over-sized mod/cons and those that have chopped the house up into zones. If you like sleeping in cooler bedrooms, use TRVs for them. Mod/cons do not handle deep temperature set-backs. If you let the whole structure get to 55*, the mod/con doesn't know that. My 2 cents

gennady

forget zoning

you will kill all efficiency with zoning.

jonny23

no zones

So one thermostat would control the 3 loops for the baseboard runs?

gennady

thermostats

there is no need for thermostat

jonny23

OK

No offense taken. Thanks for the explanation. I'm just trying to learn here and gain some knowledge about optimal system design for my situation. So say I go with no zones as suggested . . . the 2 loops to the 2nd floor are still needed as is the 1 for the first floor. Does each loop still have its own pump that gets triggered when the boiler gets a call for heat? Like I said I am not a professional. And if there is no need for a thermostat as Gennady states is this because there is an indoor temp sensor installed with the system and desired temp is set at the boiler panel?

gennady

pumps

you can have pumps for each zone or one pump for whole system. just pumps must be the right one, to provide proper GPM and head. contemporary systems are constant flow system. temperature of the water is determined by outdoor reset. There is no call for heat system operates 24/7 , except warm weather shutdown.

gennady

sensor

there is outdoor sensor. it tells boiler what temperature of the water to the heating system should be.

GordoG

No thermostat?

How does an outdoor reset control indoor temperature and account for any heat gain through windows or added heat loss caused by wind?

jumper

30 mBtu ?

If your house is really that well insulated, I'd research electric radiant.

gennady

variations

Variations in load can be controlled by TRVs or , when i install complete system with reversed return, i use deltaT pumps.

gennady

indoor reset

I was thinking about using indoor reset as well. Probably on next project.

gennady

duplicate

duplicate