Calorifier removal help

[Onewheeler]

42 minutes ago, Mike the Boilerman said:

On a household system there will be two PRVs. One in the cold water supply to the calorifier, and another connected directly into the calorifier. The second is actually a "temperature and pressure regulator", and also opens if the temperature in the calorifier rises above 90 degrees C. 

 

Is that not for direct feed systems only, or am I behind the times? (It would not be unusual!)

Are the plastic containers indicative of where the leaks are coming from? It looks from the slightly fuzzy photo as if there is a bead of water on the tee-fitting above the white container.

[MtB]

On 21/06/2017 at 08:58, Onewheeler said:

Is that not for direct feed systems only, or am I behind the times? (It would not be unusual!)

No it's direct feed, known in the world of building as 'unvented', the same as a boat calorifier.

I.E. no open vent pipe on the outlet discharging over a header tank.

[Onewheeler]

1 hour ago, Mike the Boilerman said:

No it's direct feed, known in the world of building as 'unvented', the same as a boat calorifier.

I.E. no open vent pipe on the outlet discharging over a header tank.

OK! I've never come across one before but it does seem a good idea. A quick search shows nothing available at under 4 bar, which is a bit high for many calorifiers. How many boats actually have one fitted? One could tee-off a separate PRV at a lower pressure rating.

[Tony Brooks]

7 hours ago, Onewheeler said:

OK! I've never come across one before but it does seem a good idea. A quick search shows nothing available at under 4 bar, which is a bit high for many calorifiers. How many boats actually have one fitted? One could tee-off a separate PRV at a lower pressure rating.

I don't fully understand what you are saying but ordinary "boat type" PRVs are available from 1 bar or less.

The PRV spec. should be given by the calorifier manufacturer and not exceeded but when a higher pressure water pump is fitted or the pressure switch fails people have been n known to "cure" the problem by fitting a higher pressure PRV or, as may be the case here, totally removing it.

[Onewheeler]

22 minutes ago, Tony Brooks said:

I don't fully understand what you are saying but ordinary "boat type" PRVs are available from 1 bar or less.

We are discussing combined thermal and pressure relief valves. I've never seen one in a chandlers, or a DIY shed come to that. Lowest pressure available on a quick search is 4 bar, most are 7 bar or more.

[Tony Brooks]

6 minutes ago, Onewheeler said:

We are discussing combined thermal and pressure relief valves. I've never seen one in a chandlers, or a DIY shed come to that. Lowest pressure available on a quick search is 4 bar, most are 7 bar or more.

I do not see any need for thermal relief valve - if that means it vents the cylinder if it overheats.

Many boats have thermostatic mixing valves fitted and unless you have a solid fuel stove the water transferring heat into the calorifier is controlled by the engine or central heating thermostat. This is why some marine engines with fresh water cooling may have a thermostat around 66C. Many boilers also have a safety cutout overheat thermostat.

 

 

 

[OldGoat]

It's a shame to junk a SOUND calorifier (if it is sound) and replace it with something a lot smaller - as the hot water won't last long once the heating is off etc.

Mikes too big at 80l (but's nice to have at least two showers at lest from a tankful). 15l is not a lot. But then it may be just me....

[WotEver]

13 minutes ago, OldGoat said:

It's a shame to junk a SOUND calorifier (if it is sound) and replace it with something a lot smaller - as the hot water won't last long once the heating is off etc.

It'll last even less time if relocated outside. 

[Onewheeler]

4 hours ago, Tony Brooks said:

I do not see any need for thermal relief valve - if that means it vents the cylinder if it overheats.

Many boats have thermostatic mixing valves fitted and unless you have a solid fuel stove the water transferring heat into the calorifier is controlled by the engine or central heating thermostat. This is why some marine engines with fresh water cooling may have a thermostat around 66C. Many boilers also have a safety cutout overheat thermostat.

The engine thermostat does not control the coolant temperature if the thermal output from the engine is too high for it to control. My engine regularly goes way above the engine thermostat temperature as most of my cruising is at 8 - 10 km/h. I'm not in the market for a thermo/pressure relief valve, but where the engine coolant could exceed 100 C without raising an alarm it could be argued that there is a case for a combined parameter valve to protect the occupants from secondary side boiling. An engine temperature warning set at an accurate level under 100 C would be more useful: I am not convinced of the accuracy of the one on our engine although it should be under 100 C.  The pressure cap on the primary coolant is, according to the manual, 13 psi, which with antifreeze added could enable it to reach 124C before relieving. It therefore does not give significant protection to anything but the engine.

Open to argument over whether a thermo/pressure relief valve improves safety...

Martin/

 

[Scholar Gypsy]

4 hours ago, Onewheeler said:

The engine thermostat does not control the coolant temperature if the thermal output from the engine is too high for it to control. My engine regularly goes way above the engine thermostat temperature as most of my cruising is at 8 - 10 km/h. I'm not in the market for a thermo/pressure relief valve, but where the engine coolant could exceed 100 C without raising an alarm it could be argued that there is a case for a combined parameter valve to protect the occupants from secondary side boiling. An engine temperature warning set at an accurate level under 100 C would be more useful: I am not convinced of the accuracy of the one on our engine although it should be under 100 C.  The pressure cap on the primary coolant is, according to the manual, 13 psi, which with antifreeze added could enable it to reach 124C before relieving. It therefore does not give significant protection to anything but the engine.

Open to argument over whether a thermo/pressure relief valve improves safety...

Martin/

 

Does this suggest that your skin tank (or heat exchanger if you have one) is a bit undersized? I understood that the pressurization was to reduce local  boiling near hotpsots in the engine, not to enable the coolant leaving the engine to be much hotter than the thermostat rating? 

[Tony Brooks]

2 hours ago, Scholar Gypsy said:

Does this suggest that your skin tank (or heat exchanger if you have one) is a bit undersized? I understood that the pressurization was to reduce local  boiling near hotpsots in the engine, not to enable the coolant leaving the engine to be much hotter than the thermostat rating? 

I think you have it in one - unless the temperature gauge/sender is faulty or mismatched.

[Onewheeler]

4 hours ago, Scholar Gypsy said:

Does this suggest that your skin tank (or heat exchanger if you have one) is a bit undersized? I understood that the pressurization was to reduce local  boiling near hotpsots in the engine, not to enable the coolant leaving the engine to be much hotter than the thermostat rating? 

Yes, it probably is, but at our normal speeds the temperature seldom goes into a region that gives me concern.  Pushing against a river in flood needs a careful eye on the temperature gauge though!

[Tony Brooks]

When needs must remember draining al the hot domestic water off will give you a fair bit of extra cooling until the calorifier heats up again. Alternatively if you have a twin coil calorifier and can put the central heating pump on without its boiler (if you have one) you can dump heat via the radiators.