Hidden costs of changing to a combi

[bernardgreen]

60 houses built with conventional boilers ( 10 maybe 16 Kw ) and hot water cylinders had an adequate gas supply in the 1980. Over the years more and more boilers on those houses were replaced with combi boilers. ( as much as 40 kW or more when running a shower )

As a result peak gas demand increased and the gas supply to the area needed to be upgraded.

Work started last Monday

Problems with the existing gas mains through the village were discovered when the work began. This means an emergency closure of the village High Street, a busy through route, is un-avoidable.

Informally one of the Cadent people mentioned that there are many similar locations around the UK where the increased peak morning demand from new combi boilers running showers is taking the location's gas supply close to if not beyond it's maximum capacity.

The work to improve supplies adds to transportor costs which eventaully are added to the price of gas to the consumers.

 

[picasso]

Thats progress for you.

 

[oilboffin]

I went to a lecture over two years ago on this same thing.I think it's a matter on which most RGIs
are aware of and allow for when sorting out gas pipe sizes.Bob

 

[JohnD]

Problems with the existing gas mains through the village were discovered

So is the closure of your High Street a result of these pre-existing defects?

Network reinforcement of utilities infrastructure is, and always has been, a constant task.

Some more houses will have been built since 1980, as well.

 

[bernardgreen]

Network reinforcement of utilities infrastructure is, and always has been, a constant task.

Probably, but the point is that gas consumption at peak times is something overlooked when people decide to change to a combi. ( or are mis-sold a combi as being a more efficient boiler system )

You cannot install an electric motor over 1 kW or welding machine without notifying the local electric supply DNO ( lots of people do ignore that clause in the contract ).

If the motor start up current trips the breaker or takes out the main fuse the situation remains safe. If it affects neghbours with volt drops and flickering of their ights then the DNO will act, invariably the use of the offending equipment is prohibited. .

You cannot do similar usage limitations for a gas supply, If high demand drops the pressure in the mains then hazardous situations of low pressure at appliances may arise. Neighbours would be un-likely to become aware of a pressure drop in the mains until it affected their appliances. ( the pressure regulator at the meter cannot boost pressure if the mains pressure is below the pressure required in the property ).

Maybe there should be a similar clause in domestic gas supply contracts. Notification if you are going to install a 40 kW boiler and permission from the gas transportor.

 

[JohnD]

I don't know how load forecasting is done in the gas trade. I'm sure they monitor planning of new housing and commercial developments, and know average usage patterns by homes. I would hope they can track gas flows locally online, so will be aware of peaks. The district you mention may have been scheduled for upgrade for a few years. They can probably see need for upgrade long before the average customer sees a problem.

Utilities companies like spending money on network reinforcement, because it increases the nominal value of the assets on which they are allowed to earn a return.

 

[ianmcd]

Probably, but the point is that gas consumption at peak times is something overlooked when people decide to change to a combi. ( or are mis-sold a combi as being a more efficient boiler system )

You cannot install an electric motor over 1 kW or welding machine without notifying the local electric supply DNO ( lots of people do ignore that clause in the contract ).

If the motor start up current trips the breaker or takes out the main fuse the situation remains safe. If it affects neghbours with volt drops and flickering of their ights then the DNO will act, invariably the use of the offending equipment is prohibited. .

You cannot do similar usage limitations for a gas supply, If high demand drops the pressure in the mains then hazardous situations of low pressure at appliances may arise. Neighbours would be un-likely to become aware of a pressure drop in the mains until it affected their appliances. ( the pressure regulator at the meter cannot boost pressure if the mains pressure is below the pressure required in the property ).

Maybe there should be a similar clause in domestic gas supply contracts. Notification if you are going to install a 40 kW boiler and permission from the gas transportor.

yet again Benny boy you are talking tosh, all combination boilers are modulating boilers so worst case scenario is reduced flow rate of hot water at given temperature , nothing unsafe about it, just inconvenient

 

[durhamplumber]

I went to a lecture over two years ago on this same thing.I think it's a matter on which most RGIs
are aware of and allow for when sorting out gas pipe sizes.Bob

ROFL.......you live in cloud cuckoo land.

 

[bernardgreen]

all combination boilers are modulating boilers so worst case scenario is reduced flow rate of hot water at given temperature , nothing unsafe about it, just inconvenient

That seems to suggest that if there is insufficient gas for full naximum output in the combustion chamber then the boiler will modulate ( reduce ) the flow of water to a flow rate that the available gas can heat to an acceptable temperature.

Does a boiler really modulate down the rate of combustion if it detects that the gas pressure is below normal.

Maybe this is something that interlinked boilers will be able to do, they talk to each other, add up their total gas consumption and, if it is more that the local netwrok can supply some of the boilers modulate down to keep gas comsumption below the deliverable maximum

 

[John D v2.0]

Maybe there should be a similar clause in domestic gas supply contracts. Notification if you are going to install a 40 kW boiler and permission from the gas transportor.

I think it's 70kw for a domestic supply.

Regarding the original issue, It's just the same as the argument about electric cars - once everyone starts charging overnight with 30A+ the network is going to suffer because the network wasn't designed for it. But then they can just close all the petrol stations and install massive grid connected battery containers there instead!

 

[ianmcd]

No the water flow rate will remain constant, the gas rate if reduced will not be able to keep up with the amount of water flowing through the appliance, resulting in colder water at the outlet, nothing unsafe about it, with fixed rate appliances there might be an unsafe situation as the burner is designed to burn at that set mixture and requires the fixed inlet pressure , but modern boilers are all modulating and will be safe regardless of the inlet gas pressure

 

[oilboffin]

Not allowed to run a 1 kw motor at 1kw you are only taking 4amps an electric kettle takes more.Bob

 

[John D v2.0]

Not allowed to run a 1 kw motor at 1kw you are only taking 4amps an electric kettle takes more.Bob

I think it's the inductive startup load that's the problem, not the constant power consumption.

 

[oilboffin]

There was a lecture organised by a green forum and I thought why not and bumped into loads of other lads who did gas one of whom told me he'd been allowing for this since he spoke to a BG man in a village who informed him that some villages have a reduced flow because when the gas was piped to them only small pipes wrer use because only a few properties had gas and over the years the number of houses with gas went up but the size of mains remained the same,but as Ian says modulating boilers ok but the fixed rate apps arent.Bob

 

[John D v2.0]

There was a lecture organised by a green forum and I thought why not and bumped into loads of other lads who did gas one of whom told me he'd been allowing for this since he spoke to a BG man in a village who informed him that some villages have a reduced flow because when the gas was piped to them only small pipes wrer use because only a few properties had gas and over the years the number of houses with gas went up but the size of mains remained the same,but as Ian says modulating boilers ok but the fixed rate apps arent.Bob

How do you allow for insufficient pressure at the meter? Other than fitting electric heating.