gas combi boiler

Sparkpea

just wondering if your mains water supply is off and u have a gas combi boiler can you still have ur heat on?

I dont know alot about gas boilers and some friends have asked me this question so thought someone here could feed my knowledge. I thought if the heating system had pressure in it from an internal expansion tank in the gas boiler casing then it would be ok to switch to CH only and run the heating.

No problem running a combi without mains, it's the same as not turning the tap on.

heinbloed

As far as I know there is a safety device build-in, as soon as the pressure drops to a certain level the boiler won't fire. But better check the manual.

Joey the lips

We done a combi that had a button to switch to heat only if the mains was gone.

Aside from that i imagine there would be an imbuilt safety as it needs at least half a bar to open the valve anyway...

The combi boiler works the same as a system boiler in respect of system pressure requirements, the question is if the system water pressure is correct what impact would there be to the boiler if the mains pressure required to activate the water heating side was off.
No effect at all mostly because the boiler needs the mains flow to fire for hot water, the only thing to watch for is if the boiler has a mode to preheat the plate heat exchanger, if their is no water in the plate heat exchanger the boiler may keep sending heat to it instead of the heating circuit.

pria

I am making renovations to my house. It is semi-detached house the floor area 76.76ms (826 sq.ft). I was given a quote for:
1. Estimate to remove all existing plumbing and boxing through house, relocate immersion cylinder, replace water tank in attic, re-plumb hot/cold supply to house (inc bathroom + kitchen), replace and relocate the boiler and recommission, re-plumb exterior gas line with new line to boiler and kitchen, replace and relocate rad in front bed room and downstairs bathroom.

Total estimated cost including materials and labour €6700

2. Estimate to remove all existing plumbing and boxing through house, replace existing boiler with new combi boiler, re-plumb hot/cold supply to house (inc bathroom + kitchen), re-plumb exterior gas line with new line to boiler and kitchen, replace and relocate rad in front bed room and downstairs bathroom.

Total estimated cost including materials and labour €6100. What do you think about this price?? :mad: I was informed that buying the combi gas parts in the north of Ireland is worth the trouble - financially

I cant help you with the price but to help with your decision I think removing a cylinder and replacing with a combi is normally done for a reason i.e...... to save space or reduce installation cost with the understanding that a combi works differently to stored hot water.

You would first need to confirm you're property is suitable for a combi as you're incoming mains will have a impact on the hot water performance if it is to weak/slow, the size of the boilers kw output should be looked at as the bigger the boilers kw output the better the hot water performance at the tap, the heating kw output can be reduced to the required heating load and you can run your rads at a lower temperature than you could normally with a boiler and cylinder installation .

A electric shower is always handy as a back up if the combi boiler breaks down, as for boiler parts look for a manufacture that gives you at least 5 years parts and labour warranty and if you go for a popular model then parts can be got on the Internet cheaper than some suppliers here