One Pipe System

[mikep93]

Hi,

We have just moved into a house with a one pipe gravity fed heating system. The boiler is relatively new and works fine, the 5 radiators upstairs all get hot and work fine, but the 4 radiators downstairs only get warm, not enough to heat the downstairs to a decent temperature.

The boiler (Ecotec 428) has been moved into the attic by the previous owners, could this be the cause?

 

[ianmcd]

just change it to a standard flow and return system , the 4 series was never designed for a one pipe system, surprised it works at all

 

[stem]

Unfortunately, that's the way one pipe systems work. Hot water from the boiler arrives at the first upstairs radiator, where it looses some of its heat, it then passes to the next radiator where it looses a bit more before going to the next and loosing yet more....and it continues, each radiator getting slightly cooler water than the one before. So by the end of the loop much of the heat is lost. The more radiators there are the worse it becomes.

Usually with a properly designed one pipe system the radiators at the end of the loop are larger to take the heat loss into account. Fitting TRV's to the radiators often helps as the upstairs rooms get warmer the TRV's close and allow the hotter water to travel further around the loop.

Ianmcd, has given you the ideal solution though.

 

[muggles]

That's going to kill your boiler fairly quickly too. It's massively oversized for the system as well as being fitted to an unsuitable one-pipe (which I think invalidates the warranty).

I suspect part of your problem is down to this over-sizing - the boiler is hitting its maximum temperature and shutting off before the system is up to temperature, because the system can't get the heat away fast enough.

Upgrading to a modem two-pipe system will help massively, but you may ultimately find that you need a new boiler as well which is better sized to the system.

 

[mikep93]

I have tuned the boiler down to only 13Kw and partially closed the valves on the upstairs radiators, is there anything else i can do in the mean time to improve the heat flow to downstairs?

From what i gather, a boiler on a gravity fed system should be downstairs? so as the water cools and falls to the downstairs radiator, the boiler is nearby to begin the cycle again. With the boiler in the attic, how is the cooler water downstairs returning back up to the boiler?

 

[muggles]

It has a pump to circulate the water. You're getting confused between gravity circulation and open-vented systems

 

[ianmcd]

you are confusing your open vent system with a gravity HW system two totally different things

 

[muggles]

you are confusing your open vent system with a gravity HW system two totally different things

Snap, or jinx, or whatever it is the kids say now

 

[garyo]

My house has a one pipe system split over two floors (ie. two one-pipe systems in effect) . Both independently pumped. Another option for you that might be easier than a full conversion to two pipe.

 

[mikep93]

Even when i turn off all radiators upstairs, the downstairs radiators dont get any hotter? Is this a sign that the pump inst doing its job then? All radiators have been bled.

 

[JackK]

Wow strange to hear this - I wonder if the poster did in fact get the house replumbed !

 

[ericmark]

Test the temperature of the pipes to and from radiators, it should get slightly cooler after each radiator but the by-pass pipe needs to allow water to travel without going through radiator and the inlet needs to be high and outlet low

if a by pass is blocked, turning the radiator off will stop all working. It is thermo syphon through the radiator but not whole system thermo syphon, so lagging the inlet pipe can help with thermo syphon.

 

[Agile]

A boiler in the loft would not give any gravity flow downwards.

So you must have a pumped system.

It may need balancing but one thing is certain that you have plenty of power available.