Conventional or Indirect HW heater

RogerMiller

Hi Everyone,



I am new to the site today and have a question that I cant seem to get a good answer for using the search function.



I recently bought a house that has a conventional water heater that needs to be replaced ASAP, I knew this before purchasing the house. I believe an indirect would be the best replacement so now I need to make the right decision and need help.



For the conventional replacement it is a no brainer, replace like for like.



For the indirect, the house has a Burnham P205 boiler which according to one heating contractor can support an indirect which he recommends.



I had 2 other heating contractors come in and those guys recommend a like for like replacement of the conventional because they think it will be more efficient than having to run the boiler to heat water in the summer.



Can anyone help educate me so I can make the right decision?



Thank you,

Roger

Gary Hayden_2

Use of New Indirect with existing boiler

If it were me - I would go with the indirect and when this boiler is replaced with a condensing boiler - then you can still use the indirect. The boiler will only fire to heat up the indirect during the summer if the installing contractor does not fire the boiler off the aquastat. Basically turns the boiler into a two zone system - one zone is heating the other is domestic hot water. This will also give you the least amount of trouble as far as maintenance. One thing to make sure of is that the installing contractor remembers to not take any short cuts as far as full port valves, the correct circulator size for the indirect that you select and installing purging valves and high point vents / boiler drains to get the air out of the domestic hot water tank coil.

RogerMiller

Thanks

Gary,



Thanks for the reply and the advice, I will be sure to mention that stuff to the contractor.

Zman

Plumbers like...

Plumbers like 1 for 1 replacements. Many do not understand boiler systems. I am guessing that the guy who recommended an indirect does more heating.



You boiler will heat water at 84% efficiency through an indirect. The water heater you have is likely in the 60's.



Gary made some excellent recommendations, I would also suggest DHW priority and an adjustable temp differential to assure long efficient cycles.



Carl 

Gary Hayden_2

Conventional or Indirect HW Heater

I agree with the last post with a little more explanation. When you go to 2 zones with your system, you can do this with a zoning control. This zoning control will then allow the dhw to have priority - that zone will run only to send all the heat from the boiler to the indirect. You will have a separate thermostat with sensor to turn the DHW loop off and on monitoring the tank temperature that you select.



I also install a TMV or thermostatic mixing valve on the system to allow a water temperature of 150F or what ever the greatest temperature the indirect manufacturer will allow. Then set the TMV to mix with cold water to give an out put of say 125F, that gives you 5F for losses to the fixtures. Allows you to use a smaller indirect also - I have many customers happy with 35 gallon indirects with a TMV setup. This of course depends on how much hot water your house needs at once.

Gary Hayden_2

Conventional or Indirect HW Heater

I agree with the last post with a little more explanation. When you go to 2 zones with your system, you can do this with a zoning control. This zoning control will then allow the dhw to have priority - that zone will run only to send all the heat from the boiler to the indirect. You will have a separate thermostat with sensor to turn the DHW loop off and on monitoring the tank temperature that you select.



I also install a TMV or thermostatic mixing valve on the system to allow a water temperature of 150F or what ever the greatest temperature the indirect manufacturer will allow. Then set the TMV to mix with cold water to give an out put of say 125F, that gives you 5F for losses to the fixtures. Allows you to use a smaller indirect also - I have many customers happy with 35 gallon indirects with a TMV setup. This of course depends on how much hot water your house needs at once.

RogerMiller

Great advice

Thank you very much everyone.



I have not had a chance to follow up with my contractor yet and I will definitely mention all of this info to him. I really appreciate all of the advice.



If there is anything else I need to discuss with/suggest to the contractor please let me know.



Thanks again,

Roger

Zman

Agreed

Gary thanks for the additional detail. I was a bit rushed in my response. I too like t-stat mixing valves. They are great for stabilizing todays high recovery DHW tanks and work well in the legionella battle.The potential for scalding is also eliminated.

Thanks,

Carl