boilers / water pressure advice

[Rowdey]

if i may hijack the plumber's attention for a moment...

my combi boiler has two pipes other than those dealing with cold water in/hot water out. first is copper, goes outside to a foot off the floor and nothing more. second is plastic goes outside and into a nearby waste pipe. what is the name/purpose of these two pipes? the second has become damaged, so need to know what to ask to be replaced, it has small dribble of water come out.

1st is PRV (pressure relief valve) for CH system.
2nd is condense pipe - taking away slightly acidic (tomato juice ph value) waste water to a drain. Commonly 21/21.5mm diameter - commonly found in Screwfix etc

 

[BN9 BHA]

if i may hijack the plumber's attention for a moment...

my combi boiler has two pipes other than those dealing with cold water in/hot water out. first is copper, goes outside to a foot off the floor and nothing more. second is plastic goes outside and into a nearby waste pipe. what is the name/purpose of these two pipes? the second has become damaged, so need to know what to ask to be replaced, it has small dribble of water come out.

First pipe ( copper ) pressure relief, will discharge water from boiler if there is too much pressure.
Second pipe ( plastic ) condense pipe, you may have to look up the science for this one but it's normal for water to run from this pipe.
This pipe really should go into a waste/ drainage pipe inside the property, if this pipe becomes blocked or frozen the boiler will not work or can become damaged.

 

[beorhthelm]

cheers chaps, knew the NSC oracle would save hours of trying to work it out from google.

 

[Rowdey]

I've just ordered my boiler but still questioning the boost to get.

Do you know if the mains boost refill while discharging? Or do they discharge fully & then refill = can't do same at both times.

& I've looked at iboost. & don't really understand what the difference is / why it's better?

Thanks in advance

My wife's thrown away my ST folder, but looking at docs online:

i-boost is 200l storage, and really for multi-bathrooms/big houses, prob overkill for you tbh. It's in a nice box, so looks better, is 5db quieter, but has a 1.25 overflow pipe connection requirement. approx £1100

A 'standard' mains boost extra, can be 60/80/100L storage, so i'd be minded pick the 100L.. It also doesn't need the annoying overflow connection - Approx £550

What boiler you gone for ? (just being nosey..) dont forget it can only do 10-16L HOT water p/min depending upon KW value.

Disclaimer - Above is based up internet chat help, not having seen your set up in person of course..!

 

[mothy]

My wife's thrown away my ST folder, but looking at docs online:

i-boost is 200l storage, and really for multi-bathrooms/big houses, prob overkill for you tbh. It's in a nice box, so looks better, is 5db quieter, but has a 1.25 overflow pipe connection requirement. approx £1100

A 'standard' mains boost extra, can be 60/80/100L storage, so i'd be minded pick the 100L.. It also doesn't need the annoying overflow connection - Approx £550

What boiler you gone for ? (just being nosey..) dont forget it can only do 10-16L HOT water p/min depending upon KW value.

Disclaimer - Above is based up internet chat help, not having seen your set up in person of course..!

Thanks for all your input (so far)

I've gone for an ideal vogue c40 which has 10 year guarantee if installing their system filter. It has a max flow rate of 16 litres per min.

The mains boost 100 only holds 50 litre which i think is too small. So I'm looking at the 200 which holds 100 litre = shower + other stuff, or maybe 2 weak showers at 8 litres per min.

The only thing not sure on is the 100 has max flow rate of 16lpm & the 200 24lpm. What happens if i chuck 24lpm at the boiler? Does it restrict it or do i get cold water or waste 8lpm (somewhere)

 

[Rowdey]

Thanks for all your input (so far)

I've gone for an ideal vogue c40 which has 10 year guarantee if installing their system filter. It has a max flow rate of 16 litres per min.

The mains boost 100 only holds 50 litre which i think is too small. So I'm looking at the 200 which holds 100 litre = shower + other stuff, or maybe 2 weak showers at 8 litres per min.

The only thing not sure on is the 100 has max flow rate of 16lpm & the 200 24lpm. What happens if i chuck 24lpm at the boiler? Does it restrict it or do i get cold water or waste 8lpm (somewhere)

Yes, your right -100=200L storage

Vogue 40 - FAT..! Comes with 16.4l/p/min DHW restrictor built in, so no wastage.

What other gas appliances you got in house? At full chat, that boiler wants 4m3 gas p/h, and a standard meter will only let 6m3 through, so i hope you dont have (say) a gas oven, a fire and 6 burner gas hob clunking away too..!
Either way, your likely to need to upgrade gas pipe diameter from meter to boiler i'd say.. something to watch when your Gas Safe engineer does a quote.
I know there are some guys on here, and i'm not sure where you are based, but if near Brighton, i can recommend a good GS installer.. (not me, my brother.)

 

[mothy]

Yes, your right -100=200L storage

Vogue 40 - FAT..! Comes with 16.4l/p/min DHW restrictor built in, so no wastage.

What other gas appliances you got in house? At full chat, that boiler wants 4m3 gas p/h, and a standard meter will only let 6m3 through, so i hope you dont have (say) a gas oven, a fire and 6 burner gas hob clunking away too..!
Either way, your likely to need to upgrade gas pipe diameter from meter to boiler i'd say.. something to watch when your Gas Safe engineer does a quote.
I know there are some guys on here, and i'm not sure where you are based, but if near Brighton, i can recommend a good GS installer.. (not me, my brother.)

Ok cool. & good news. I have an installer & he's told me i need to upgrade the supply from meter from 22mm to 25mm (currently floor is up waiting screeding so no issue). Hope thats right (25mm).

No other gas appliances in the house other than a 5 ring hob? It does need to power 25m2 of underfloor heating too (which may increase to 60m2 in future). So I'll have to consider all those when heating is on & the gas hob is like a camping stove..

Edit: ive done a bit of research & looka like 6m3 = 66kw. So combi of 40kw & hob gives plenty of headroom. I'll have to consider the effect of having heating on as well as hot water though. Thanks forall assitance.

Off to research dhw restrictor..

 

[Rowdey]

Ok cool. & good news. I have an installer & he's told me i need to upgrade the supply from meter from 22mm to 25mm (currently floor is up waiting screeding so no issue). Hope thats right (25mm).

No other gas appliances in the house other than a 5 ring hob? It does need to power 25m2 of underfloor heating too (which may increase to 60m2 in future). So I'll have to consider all those when heating is on & the gas hob is like a camping stove..

Edit: ive done a bit of research & looka like 6m3 = 66kw. So combi of 40kw & hob gives plenty of headroom. I'll have to consider the effect of having heating on as well as hot water though. Thanks forall assitance.

Off to research dhw restrictor..

28mm pipe.

Hob will be no more than 11kw

Combi is DHW priority, so water OR heating demand get met, not at same time.
25m3 = no more than 5kw (unlikely more than 200watts/p/m2)

DHW restrictor is mentioned top right page 28 of manual..

Good luck

 

[mothy]

28mm pipe.

Hob will be no more than 11kw

Combi is DHW priority, so water OR heating demand get met, not at same time.
25m3 = no more than 5kw (unlikely more than 200watts/p/m2)

DHW restrictor is mentioned top right page 28 of manual..

Good luck

Final bit from me. The mains boost 200 is £750 & will be sighted in the cupboard with stop cock in. So I'm thinking of installing boiler (knowing i only have 12 litre per min coming in) & seeing how ut goes. As i can retro fit the mains boost at anytime i choose to go for it.

Thanks again