- Thread starter knighty
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gaz1
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the older systems use to use a bypass system to preheat the water before the boiler as it stopped thermal shock from happening
as it was used on the old cast iron boilers
bypassed from the output side to the inlet side before the pump similar to the gravity fed systems
it also amps your temperature exiting the boiler but on these newer boilers they would more likely shut down the boiler as most boilers have a bypass within them
i presume you get the 80c out of the exchanger when hot already ?
if not you need a higher input into the heat exchanger as your heat exchanger is too efficent and draining all of the heat from the water returning the water cooler than what your needing
thats why you need a higher input temperature into the heat exchanger
are you running your system in series or parallel as you can gain high heat with a parallel heating system
as it was used on the old cast iron boilers
bypassed from the output side to the inlet side before the pump similar to the gravity fed systems
it also amps your temperature exiting the boiler but on these newer boilers they would more likely shut down the boiler as most boilers have a bypass within them
i presume you get the 80c out of the exchanger when hot already ?
if not you need a higher input into the heat exchanger as your heat exchanger is too efficent and draining all of the heat from the water returning the water cooler than what your needing
thats why you need a higher input temperature into the heat exchanger
are you running your system in series or parallel as you can gain high heat with a parallel heating system
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I don't have a heat exchanger yet, I have two gas water heaters which I want to change for a heat exchanger... (because gas water heaters are overly complicated for what I need)
if I change to a system boiler I don't need to worry about the heating side of the system, the boiler ill modulate up/down/on/off as needed
if I change to a system boiler I don't need to worry about the heating side of the system, the boiler ill modulate up/down/on/off as needed
Barking Mat
Cuddler of hedgehogs.
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We use smaller ones on our boats, but only 16mm bore pipe.
I'll try and find some details tomorrow, if that helps.
I'll try and find some details tomorrow, if that helps.
that'll be good thanks :-)
I found these... https://www.mandmcontrols.com/003n0909-danfoss-avta-25 bit it looks overly accurate/fragile for what I need?
I found these... https://www.mandmcontrols.com/003n0909-danfoss-avta-25 bit it looks overly accurate/fragile for what I need?
Barking Mat
Cuddler of hedgehogs.
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- 13,490
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- France, Brittany.
This is what we use on our boats:
www.delawarepaddlesports.com
Quick Thermostatic Mixing Valve Kit f/Nautic Boiler B3 [FLKMT0000000A00]
Thermostatic Mixing Valve Kit for Nautic Boiler B3A thermostatic mixing valve is a valve that blends hot water with cold water to ensure constant, safe shower
www.delawarepaddlesports.com
I was re-reading your post - you need the valve to open once you reach a certain temperture? The only valve that I know of that can do this is a Herz thermal balancing valve.
They are really meant for large domestic hot water return systems where you can up the temperature over say a weekend. The valve senses the high water temp and stops doing its normal regulating function and opens fully to allow a high flow of hot water to pasturise the circuit. It might work for you. Herz valves UK are also pretty helpful and know their stuff. The only snag is that they only seem to do it up to 3/4" so you may need to have 2 or 3 valves in parallel if you went down that route so it would depend on hte cost of them. I havent used these in ages and cant remember what they cost.
They are really meant for large domestic hot water return systems where you can up the temperature over say a weekend. The valve senses the high water temp and stops doing its normal regulating function and opens fully to allow a high flow of hot water to pasturise the circuit. It might work for you. Herz valves UK are also pretty helpful and know their stuff. The only snag is that they only seem to do it up to 3/4" so you may need to have 2 or 3 valves in parallel if you went down that route so it would depend on hte cost of them. I havent used these in ages and cant remember what they cost.
I'll try Herz tomorrow
my problem is the flow rate will change depending on the water temp into the heat exchanger... cold mains water the flow will drop right down, but when it's just circulating tank water (no draw off) the input temp will steadily rise... soI could do with increasing flow to match and keep the boiler working 100% and reheat the water asap
I figure a valve that's opening/closing to keep water tank at 80'C will solve all my problems
my problem is the flow rate will change depending on the water temp into the heat exchanger... cold mains water the flow will drop right down, but when it's just circulating tank water (no draw off) the input temp will steadily rise... soI could do with increasing flow to match and keep the boiler working 100% and reheat the water asap
I figure a valve that's opening/closing to keep water tank at 80'C will solve all my problems
addjunkie
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The more you describe to system the more It needs more than just a simple valve. Youve multiple variables
the heater and the tanks are in parallel
there's a pump sending water through the heater
when we draw off water it flows through both the heater and the tanks
when there's no water draw off water is pumped through the heater and backwards through the tanks
what I have now works well.... if I could find some decent gas water heaters
but I can't, so I'm swapping to a system boiler and heat exchanger
the problem is the gas water hearers used to restrict flow through themselves to keep the temperature right
with unrestricted flow through the heat exchanger I'll pull fresh cold water through it faster than I can heat it, and when the tanks are cold the pump will pump it through too fast so it's barely warm
the two I have right now are made by Rinnai
I think long term a system boiler and a heat exchanger would be better, keeps the fresh water out of the boiler (hard water area here too)
if I could find a valve a bit like a car thermostat, almost closed at low temp, wide open at 80'C then I'd be sorted
I think long term a system boiler and a heat exchanger would be better, keeps the fresh water out of the boiler (hard water area here too)
if I could find a valve a bit like a car thermostat, almost closed at low temp, wide open at 80'C then I'd be sorted
