Indirect water heater

John_56

Went on a call today for an indirect water heater we installed this past summer. The complaint was when they tried to fill the single whirlpool tub, they would run out of hot water about half way. I found the low voltage wiring was done wrong, it did not fire the boiler on a call for hot water. I fixed that and raised the boiler water temp to 185. Thought I had it solved until I tried filling the tube, it appears that I empty the 'stored' hot water and then must wait for the recovery. My tech support said, "well, it should work".......
Anyone have any suggestions? I have not had much experience with indirects, so I am feeling kind of helpless here. By the way, I have a 30 delta T across the coil and it is wired priority over all other heating units.
Thanks,
John

curiousity kills

indirect

install a tempering valve on the hot water line and raise the indirect to 145 and set the temp valve to 125 this should give you 10 to 15 gallons more.if this does not help you will need a larger tank.

Maine Ken

What is the output of the boiler? A small boiler coupled with a big tub equals a very dissatisfied customer!!!

Confused_2

wiring

If the low voltage wiring was not firing the boiler how did the indirect ever get hot in the first place? The aquastat wiring on the indirect should run to the priority zone of the controller. Kicks on the boiler when the "aquastat" hits it's low limit and calls for the boiler to recovery it's heat.

ernie_3

and yet.....

No one mentions gallons per minute flow rate. Check the specs on the indirect literature. Check the flow rate w' a bucket and a watch. No matter how big or small the indirect is if the h/w outlet exceeds the mfg flow rate you'll never recover in time to fill it full. I suggest if you slow down the fill rate of the tub, you'll fill it w' ample recovery.

hr

What size tank and

what size tub? Just no substitue for a dump load capacity when fast filling tubs

Rare for me to go below 40 gallon indirect, unless you have some serious BTU with pipe& pump sizing to drive it.

hot rod

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jaybee

i,m new if u will can explain this to me?I dont understand.

John_56

My guy wired the aquastat into the correct place, but the boiler was left to fire on it's own temp control set under 140.

John_56

The tank is a W/M 60, 42 gallon tank, the boiler is 250 mbtu output. I have not looked up the specs on the recovery rate. Checking the actual flow at the tube is a great idea, thanks.
John

curiousity kills

explain to jaybee

if your refering to my quote, by installing a mixing valve and raising the temp on the tank cold entering the mix valve will mix with the higher temped indirect mixing it to desired temp using an eight to one ratio this will stretch the hot water supply.This is not to say this install has other sizing issues but might be better than replacing equipment.Some towns require this on all installs of water heaters to prevent leginares desease.

Nron_9

Zone valve

Do you have a zone valve or pump for the domestic ,if its a zone valve what is the cv for the valve you may be undersized for decient recovery with 250 Mbh , what flow rate does the spec sheet say for flow through the coil ?

Pinball

30 delta T?

> Do you have a zone valve or pump for the domestic

> ,if its a zone valve what is the cv for the valve

> you may be undersized for decient recovery with

> 250 Mbh , what flow rate does the spec sheet say

> for flow through the coil ?

Pinball

30 Delta T?

I know this might sound silly but I have a few questions about this . Since this is a W/M, how did you get a 30 Delta T across the coil? W/M has a tank in tank design. This isn't hooked up to the old tankless coil by some chance is it? I'm not trying to insult anyone here but an indirect is NOT an aquabooster.It is designed to run as an additional zone.(if you have never had experiance with these things you could have made a simple mistake) Is it possible to post a few picts.showing the piping configuration?

ScottMP

I think he

just used the wrong terminology. Or you may have hit the real problem :0.

I agree with HR, theres NO substitute for gallons of storage to gallons of tub fill. If the tub is 78 gallons and you only have 42 gallons of storage ..... uh oh.

If this is the case I would try the mixing valve and raise the temp in the tank. I try and alway use a set point controller that has better sensitvity to temperature. You get better responce time than you would from a basic aquastate which could be off by as much as 15 degrees.

Scott

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