3 Boilers versus 12 What is the best choice

[Therm]

I propose to install 3 x 4 MW output boilers i.e. (3 x 13,648,000 Btu/Hour) into a large MTHW space heating system operating on a constant temperature and variable flow principle (I.e. 3 way diverting valves at air handling units).

Another party has proposed using 12 x 1 MW output boilers i.e. (12 x 3,412,00 Btu/Hour).

The second proposal seems to me one that would prove problematic in terms of control and could result in poor operating efficiencies.

I would appreciate some for/against ponts from any experienced designers.

Regards

Therm

 

[svanels]

Some considerations:

1) What is your steam demand?
2) What is your peak demand, and your lowest demand
3) 12 boilers demand more spare parts, a larger maintentence support, and probably some of the boilers will be permanently out of service, which bring the problem of conserving or holding the boiler on hot standby.

Regards Steven van Els
SAvanEls@cq-link.sr

 

[Therm]

Steven,

Thank you for your response. I agree with your point on maintenance.


There is no steam involved, only MTHW space heating. Utilising 125 deg C flow/ 95 deg C return. (257 deg F / 203 deg F)

The full load is the boiler load. Partial load will vary during the heating season. On average this would work out to be about 60% in milder weather.


The intention is to link the 12 boilers together into a modular arrangement. The burners would be controlled on flow temperature to shut off one at a time according to the temperature demands.

Regards

Therm

 

[Jonkatz]

MOst heating plants I've seen use 3 or 4 boilers or hot water generators. (12) will for sure be harder to control, harder to maintain ( and just unneccessary in my view) Not to mention will end up being considerably more expensive most likely.
j. katz

 

[Therm]

Jonkatz,
Thank you for your response. Your comments reinforced my own opinions and assisted me in ensuring that a sensible design approach was taken.

Regards

Therm.