Boiler upgrade

Andrea2013

Hi,

I live in the NE. I just moved into an old house built around 1950. The house has a tankless gas water boiler for heating and domestic hot water. Boiler is old Burnham holiday of over 50 years old with 150,000 BTU input and 120,000 output. House has 2 floors with around 1,800 square ft and has very poor insulation We have two zone heat : one per floor. I have 2 questions:

1- the water in the shower gets freezing when the hot or cold water is used elsewhere in the house. We can't use washing machines, dishwasher or even wash our hands without making the other person freeze in the shower. What is the problem and what could be the solution?

2- I would like to retrofit this old boiler and I'm looking into going with more efficient gas boilers or maybe mod con boiler. Currently I have baseboard heat with 180 degrees water supply. I've been reading a lot about how mod con works best with lower water temperature. I'm afraid if I go with mod con and lower the temp of the water supply in the baseboard I will not get enough heat as quick  as I'm used to it and will sacrifice the comfort in the house which for me is the main priority for heating. I have done a heat loss on my own and found out that my heat loss is 45,000 BTU. I have measured my exisitng baseboard length and I have 100 linear ft for the entire house which I believe (based on some info I found online of 550btu/lf/hr per baseboard) I should be just about right and I'm not over sized (55,000 BTU). My question should I go with high efficiency mod con or mid range effciency with cast iron heat exchanger. 

I would appreciate if someone can honestly answer this.

Thank you

Steve Whitbeck

Mod CON

 If you go with a mod con install the outdoor temp sensor and the boiler if set up properly will supply the water temperature that you will need to keep the house comfortable. I like the Lochinvar WHN model.

Andrea2013

Mod con

Thank you Steve,

I read conflicting views about using mod con with old exisitng baseboard. Some say it will work and some say it will not work and the temperature will stay cold in the baseboard.

Andrea2013

Mod con

Thank you Steve,

I read conflicting views about using mod con with old exisitng baseboard. Some say it will work and some say it will not work and the temperature will stay cold in the baseboard.

pipeking

if it gets freazing cold

then it very well may not be your boiler, i would look at the shower valve first. 1) how old is it, 2) does your shower valve have thermostatic mixing, 3) do u have a thermostatic mixing valve at the tankless,4) have these failed?

now of corse upgrading your hot water supply will give u more hot water, but runing out of hot water is differant then the hot water getting redirected.       running out: the hot water gradually gets cold. 

redirecting hot water: happens when thermostatic mixing valves r not used and when anther fixture is turned on it takes the hot water from another, which causes instant temp change.                                                

SWEI

mod/con with baseboard

Will work just great - once you adjust the reset curve properly your thermostat becomes a high limit control and should not shut the boiler off unless you have heat gain from some other source (wood stove, solar gain, etc.)  Consider using a smart circulator, which will reduce the electrical consumption by about 75% over a conventional circulator.



Proper sizing of an indirect DHW heater will cure the cold shower problem.

Jason_13

Either or

Either ones will give you a good operation at minimal fuel cost

Either one you decide on use ODR and sidewall vent. There are some lower return temp cast iron boilers on the market that will get the operational cost closer between the two products. Most fuel savings are set up by proper sizing and system efficiency.

Charlie from wmass

as time has passed I have found ModCon boilers

work very well on any system they are used with. This is as long as they are maintained and they are sized and installed properly. If your heat loss is 45kbtu and your baseboard is rated 55kbtu then you are a good candidate for a mod con boiler.

Eastman

Andrea

What are your fuel bills?