Combi conversion from vented gravity system - wall of text and questions

[DarrenThomas]

Certainly welcome to come and have a look and quote As I said before, you'll have to be able to accept a card in some way though otherwise we can't pay!

I'll drop you a PM.

 

[DarrenThomas]

If I am grasping some basics right, radiator outputs vary depending on the temperature difference between the water in the rad and the air in the room. The higher the difference the higher the heat output of the rad.

So, for example (using the info in this pdf) a Stelrad Softline 600x800 K2 with a 50c delta will output 1386w. At 40c delta it will be 1037w and at 30c it will be 714w.

So, if you planned on running with a 80c flow and 69c return, and the room was say 20c, that radiator would be putting out a fair deal of heat. However with a condensing boiler you want a return of 55c or lower, assuming the same 20c room temp then that same rad is now only shifting 860w ish.

So, if the room in question lost 1000w your choices for that particular radiator would be to a) run at a 40ish delta or b) increase size of rad to that the delta can be kept lower but still heat the room.

Did I get that right?

If so, does that mean on a condensing boiler the way to keep it most efficient is to have rads sized to run at say 35C delta rather than 50?

 

[Roger Welton]

Correct and it is this principle that weather comp works on, when cold and more heat is requires the flow temp increases to match this increase in load.

 

[DarrenThomas]

Another one.

For the condensate pipe I understand connecting to internal waste is preferred to prevent freezing.

Does condensate pipe have to be rigid or is there some kind of flexible alternative like a washing machine waste?

Also does the run from boiler to waste have to be continual drop? It couldn't run along the floor and up to said waste?

Just looking at where this is going to go and where the existing cupboards are. Even pulled the sink cupboard out to get a better look!

 

[SilentMike]

some boilers it comes out in flexible tubing but i would check with the manufactures on that one, if you pipe out side i normally upgrade the pipe to 32mm to help prevent freezing

 

[buckley plumb]

I don't normally take cards but can do through my PayPal account if the customer is happy to cover t


Sent from my iPad using Tapatalk HD

how do you do that mate

 

[DarrenThomas]

Thanks again Mike.

Can I just check that this McAlpine Flexible Condensate PipeKit is what I think it is? It's only to make the run to the sink waste easier for whomever installs as it's a little snug out there!

Flexible Condensate Pipe Kit - Condensate Fittings - Traps | McAlpine Plumbing Products

I've had two guys come for quotes today. Howsie is coming on Friday.

 

[Mike Jackson]

you can set your hot water to whatever temp the boiler allows as it is instantaneous
and there is no risk of legionellae

That is so wrong, there is legionella risk with water that is not heated above 50 degrees. There is less risk from water that is not stored at less than 50 but on long pipe runs there will be water laying at an ideal breeding temperature for bacteria. A higher temperature will sterilise the pipe each time it is used.

 

[SilentMike]

Ok maybe that's not 100% accurate but at 50 they can survive but do not multiply 66 degrees it takes 2 min to kill legionella. i suppose saying no risk was wrong but i would not be concerned about it with a combi