sealed heating system?

Question

on a sealed heating system that is fitted with thermo valves, how do i reduce damage to the pump if all the valves are not calling for heat. there is no hot water cylinder on the system. do i fit a bypass valve?, if so what type. The pump is right beside the boiler. Only 6 rads, what size of expansion vessel?.

Answer 1

Normally one valve is a manual type and left open, usually bathroom rad or towel rail. If this is not possible and all valves are fully closed (unlikely) there will be nowhere for water to circulate. You will then have to fit an automatic by-pass valve after the pump, between the main flow and returns. If there is a motorised valve you must take off before this. If the boiler has a pump overrun and there is a motorised valve you need a by-pass valve even if your valves are open, as when the timer or stat shuts the valve there will be no circuit, and you'll get kettling from the boiler, no circulation and a knackered pump.

DON'T fit a locksheild or stopcock as a bypass it wont work, it will allow hot water back to the boiler which will cut off early, and will reduce the flow in the radiators.

** Michael H.. A bypass valve is not affected by temperature, only pressure.**

Answer 2

On any heating system you should always have a 1 radiator that is not thermostatically controlled. When the programmer turns off the boiler at any time the pump should remain running for a few minutes.
The open radiator will always take heat from the boiler even when all others are closed down. This acts as a safety valve as the boiler can be at this time still giving heat. If this radiator was not open, the boiler would heat up and and the water in it would turn to steam. This could cause the main boiler safety valve to open and very hot steam would be given off at a high pressure.This could cause damage to the boiler and your house.
Get a competent heating engineer and he will ensure that all these points are allowed for

Answer 3

expansion tank should be sized for the boiler, or the water that it holds. I doon't thijnk your pump gets damaged by running with zone valves closed, at least not in my experience. But you could install a controller that ties in the pump with the energizing of the valves. With 6 rads, I'd just let it run all winter. you have extra couplings I assume?

Answer 4

Fit a differential bypass valve after the pump (Screwfix Part No: 67854-82, £14.99) and use a 6 - 8 litre expansion vessel, make sure it comes with a pressure gauge, filling loop and prv, you can get expansion vessel kits from any PTS merchant.

Answer 5

you need to fit a lock shield to create a loop after the pump. this allows for continual circulation with all valves shut.

Alternatively you can buy a dfferential bypass valve that open at certian high temp, see page 372 in the screwfix catalogue or look for part numbers 67854-83 or 98894-83 on screwfix.com

about £15-£25

Personally, I prefer to leave the bathroom rads and towel rails on.

Answer 6

First examine e book on boiler. next examine the water rigidity in boiler. could be between a million-a million.5bar. If the boiler heats the nice and comfortable water examine that the nice and comfortable water / heating swap is interior the mind-blowing place. If a majority of those standards are made then my advice is the two get a heating engineer or a boiler representative to envision out boiler.

Answer 7

It is only necessary to insure that at least one valve is open in order to run the pump. Appropriate wiring can be done.

Answer 8

If you are asking these questions it suggests you are not sufficiently trained to carry out this work.Why should an engineer who has spent a lot of time and money studying for qualifications give you this information for nothing?It is illegal to work on heating systems if you are not competant.Pay the going rate to the qualified engineer.