Potential Gas backup boiler? Thoughts anyone?

[mpilihp]

Hi all, I stumbled across these units and was wondering if it could be used as a backup boiler for when the wood boiler is off. Nofo is using a on demand DHW gas heater as a backup to is wood boiler and the concern I heard with that was they were not ment to take in HOT water to heat, that those devices are expecting 50 deg water.

This unit since its for a pool I would think would be able to accept pre-heated water. They are not overly expensive, theres a 100K for under $800.

http://www.swimmingpoolsetc.com/HAY-H100IDP1.htm

~ Phil

 

[webie]

My first thought is its not very efficient at only 81% . the funny thing here is this is a pool and spa heater , I thought there was a lot of discussion about using copper as heat exchangers for spas and hot tubs , evidently there must not be a problem seeing the exchanger is copper.

 

[mpilihp]

Yeah I thought the same thing, Nofo has had his homemade unit in for many years with no ill effect. We hardly use our oil boiler now, maybe two weeks a year we are away and its fully heats off of it and then just an occasionaly day here or there it kicks on. So a gas type heater like this would be good.

 

[ohbie1]

concern I heard with that was they were not ment to take in HOT water to heat, that those devices are expecting 50 deg water.

~ Phil

I have a Bosch on demand pilotless that I use for DHW backup. Before I had the gasifier, I preheated the water entering the on demand unit with a DHW coil in the oil burner; there was never a problem. The only thing to consider is that these units have a max. temp. as their output. If the output exceeds this temp., the unit will shut down. I think for my bosch it is about 190 °F .......not a problem, because you can regulate the Δ T with the gas valve.

 

[tom in maine]

I would not use a pool heater in lieu of a boiler.

An on-demand DHW heater like a Rinnai, Takagi or Noritz would be decent candidates and are not that much more money.
Preheated water is not going to affect them and the efficiency will be a fair bit higher.

Many of their models can function as boilers.

 

[heaterman]

My first thought is its not very efficient at only 81% . the funny thing here is this is a pool and spa heater , I thought there was a lot of discussion about using copper as heat exchangers for spas and hot tubs , evidently there must not be a problem seeing the exchanger is copper.

There is a good reason a lot of pool heaters get replaced every 6-8 years..........think about it.