Make sure it has a stainless steel heat exchanger in each section, no aluminium anywhere in the water circuits!
The Dash Away From (Natural) Gas
- Thread starter Black Hole
- Start date
Make sure it has a stainless steel heat exchanger in each section, no aluminium anywhere in the water circuits!
MikeSh
Well-Known Member
SWMBO likes a 'power shower' and over the years we tried various permutations.
Pumped - Horribly noisy, and failed when we had a power cut with guests just about to have a morning shower.
Combi - OK for shower but 20 mins to fill a bath?
That went out the door within a year.
Mains pressure HW tank - Brilliant, but when we moved the regs had changed (annual testing) and routing the safety overflow in the new (current) house was problematic as the cupboard is in the middle of the house.
So ... Thermal store. Basically a back to front copper cylinder (cold fed at low pressure from loft) where the bulk (part of the boiler/CH system) is kept hot by the boiler and the coil has mains cold water fed into it to give mains hot water out. The low volume of the coil means there is no requirement for a safety valve & vent or annual testing. It's not perfect but gives a good shower and sensible bath filling times.
I've stuck with Vaillant for boilers for some years now as they seem good (Which? recommended IIRC).
Pumped - Horribly noisy, and failed when we had a power cut with guests just about to have a morning shower.
Combi - OK for shower but 20 mins to fill a bath?
That went out the door within a year.Mains pressure HW tank - Brilliant, but when we moved the regs had changed (annual testing) and routing the safety overflow in the new (current) house was problematic as the cupboard is in the middle of the house.
So ... Thermal store. Basically a back to front copper cylinder (cold fed at low pressure from loft) where the bulk (part of the boiler/CH system) is kept hot by the boiler and the coil has mains cold water fed into it to give mains hot water out. The low volume of the coil means there is no requirement for a safety valve & vent or annual testing. It's not perfect but gives a good shower and sensible bath filling times.
I've stuck with Vaillant for boilers for some years now as they seem good (Which? recommended IIRC).
OP
Black Hole
May contain traces of nut
Shirley not! How many kW was it? My 27kW had no problem filling a bath as fast as the water would flow. Yes, OK, the Highflow had a reservoir, but that only suppled two gallons up front. This new one is specified as 35kW.
MikeSh
Well-Known Member
Not sure now ... more than 20, maybe 22 or 24.
But it was a big bath, with a bulge at one end for the shower, and we like it deep
OP
Black Hole
May contain traces of nut
Oh, well, if you're filling a swimming pool...
OP
Black Hole
May contain traces of nut
Well, it's done. No, not Valliant, but the significantly less expensive Ideal Logic C35 (35kW Combi). Yes, it has an alloy heat exchanger, but then again I don't expect to be living here in another 10 years (and even if I am, who knows what the situation will be re domestic energy). This unit is advertised (on the Ideal website) as "Ready for 20% Hydrogen", but it is not stated in the installation manual so far as I can see.
Logic Combi Boiler | Easy To Fit | Installers | Ideal Heating
Ideal's Logic Combi boilers are light and compact, designed with ease of installation in mind. Learn all about our 2 year parts and labour warranty on our websi
idealheating.com
There was a wrinkle in that these new-fangled "condensing" boilers recover what used to be waste heat from the flue emissions in the heat exchanger, extracting the latent heat of evaporation from the water vapour in the combustion products. That results in a flow of condensate which has to be disposed of, comprising water made acidic by the carbon and sulphur in the gas supply, so it has to be discharged to the foul water sewer.
As there is no convenient access to the foul drain from my boiler compartment, a sump receives the condensate drain, and the sump contains a float-activated pump which periodically sends the condensate into the roof space and there into pipework connected through to the soil stack.
An interesting point: during commissioning, my installer checked the full-blast energy consumption by monitoring the gas meter to see what volume of gas was consumed over a period of 2 minutes. The resulting measurement was 0.346 (cubic metres?), and he reckoned that meant the boiler was running at 34.6kW.
According to my gas bills, 25 "meter units" works out as 279.1kWh, so a 35kW burner should consume 3.135 units/hour, or 0.1 units/2 minutes. I don't get it. Even if I've mis-remembered and the figure was 0.034 units, it's a factor of 3 wrong either way.
MikeSh
Well-Known Member
What could possibly go wrong?
bottletop
Active Member
The only way I can get the maths to work is if we assume the installer was using imperial measurement and 0.0364 cu ft (not 0.346)!
Using something like https://www.ukpower.co.uk/home_energy/gas_meter_readings
We get 0.0364 cu ft × 30 = 1.092 units per hour = 34.5712 kWh
But - this is just guesswork (may explain why your calculations were out by a factor of 3).
OP
Black Hole
May contain traces of nut
I agree that works... but we're talking about the measurement being taken on the same meter as I get billed from!
OP
Black Hole
May contain traces of nut
I know! No alternative, but at least there is a limit switch (float) which cuts the boiler if the level in the sump reaches critical (ie about to overflow because the pump has failed or the outlet is blocked).What could possibly go wrong?
MikeSh
Well-Known Member
Freezing in the roof space could be a worry, but I suppose that as it's going to blast a lot through periodically, rather than trickling to drain all the time, that may not be a real issue.
Assuming there are no sags in any non-vertical pipework - it's plastic presumably.
bottletop
Active Member
I forgot about that. For some reason I imagined he was using a separate measuring device.
But, you're right, my calculations are very wide of the mark because there are some intermediate steps. You may be able to do the calculation yourself as using the figures he gave you - eg search for 'boiler flow rate calculation' and see if that resembles what he did etc.
prpr
Well-Known Member
But how will you know that's the cause rather than anything else?
It still amazes me that modern boilers don't have anything more than primitive user controls.
I've just had a new one (I'm still traumatised by the whole thing for various reasons) and it's got a computer brain which must have oodles of interesting monitoring stuff, but is completely inaccessible. Why hasn't it got a network port and a web server (for example)?
OP
Black Hole
May contain traces of nut
Look up "opentherm". This boiler has a data port.
Only be elimination, or by looking in the sump. But for my own satisfaction, I plan to add a warning light.