Replacement boiler considerations

[Owain Lastname]

My loungette is 14.3degC at the mo' which is comparatively warm for it.

My bedsit has no insulation.

Owain

[John J]

You really do need to consider octopus tracker tariff. It does have a risk of price surging but looking at prices over recent years it's never got up to worrying levels. The price changes daily via a smart meter and the monthly bill comes with a sheet of daily usage and prices over the period of the bill. I've just had my Dec/Jan bill which showed the average price over the period was 14.82 pence per unit.

[Harry Bloomfield Esq]

+1

[AnthonyL]

[AnthonyL]

Just looking at

Not sure that it is up to date on the minimum Heating Output. The Greenstar I've cited has a 10:1 modulation so down to 3kW.

A bit concerned that the shower flow rate seems too low for some boilers and maybe that's why the Baxi ends up cutting out the burners at times during a shower.

The WB have this as standard except I have to add the sensor.

Looking at the install notes it seems like a vertical cylinder.

I am leaning to towards the WB as I guess is evident by my postings.

I may have misinterpreted the engineer. He is on the WB recommended list. The Fernox may have saved a power flush, or even a post install chemical flush.

The WB install seems to indicate it is compulsory for the warranty extension.

Thanks

Piping is 16.2mm OD (inc paint). Hall Radiator: The inlet to the radiator is just over 25mm (1") (3/4" BSP??) and the connector has a lot of PTFE tape. Pipe centres 1360mm, radiator length 1380mm (inlet to inlet)

All the radiators have the same pipe->radiator connector fitting

Which manual? I'm really looking for what useful features other folk have. Note that I'm just single zone and all radiators have TRVs. I don't feel the need to get more sophisticated.

With just the two of us, and not a high demand for hot water (even less if I ever get the dishwasher replaced) I feel that we'd be spending money on having water, hotter than needed for health reasons, sitting around doing nothing almost regardless of the tank insulation.

We could always go back to boiling a cauldron on the gas hobs.

Not on my radar. It would really need a big investment in re-piping and larger radiators and at my age not worth it.

Yes, added as much as I could when I put the Drayton Wiser control in. Before that it was back and forth to the boiler to adjust the temperature and setting its on/off times.

[AnthonyL]

No, one of the reasons I bought it was that it is not bespoke nor locked in and it is much more than a bang on-off thermostat as I've described above.

I got it at a much lower cost from Plumbnation.

Just needs the hub connecting to the "call for heat" connections on the boiler's control panel and the WB I'm looking at has similar connectors. Room thermostat communicates via Zigbee to hub. App connects via WiFi to hub and to internet. Seems to do as much as I need but I have no experience of anything else.

WB boiler also has Weather compensation and the accessory addon to connect. As far as I can see that is totally separate to the thermostat.

[AnthonyL]

I've counted all the rooms, and counted all the radiators, and there are neither too many nor too few. Just, as I said in my OP, an undersized radiator in the study.

Not convenient. Plan B will likely be a small undersink heater and connect up the non-working/disconnected electric shower in the man bathroom (the main shower is near the boiler in the utility room).

[AnthonyL]

My starting point is my existing setup, which is just about right, refer my OP.

[AnthonyL]

It was all double glazed, and insulated (since added to). I think the only issue is that the boiler size installed in c2006 was probably taken from the original boiler size it replaced from 1969. I'm positive I can go down from the 30kW to at least 25kW based on the information I provided in my OP.

[AnthonyL]

Yes that is a bit of a block. But the issue is exacerbated by the performance of the existing boiler. So we have to wait for a while for the boiler to get up and running plus the delay in delivery, then as my wife likes to run the water, slowly, to rinse, the burners cut out, the water goes cold for a while and the screams get louder.

In the past I have questioned the Error 60 I get on this boiler. It is almost certainly due to an overheat condition (clogged heat exchanger?). If I run the boiler at a low CH temperature it fails less often, as also in this milder weather. It also fails less often if I turn the DHW down to level 1 (9 being max) when the shower is running. The burners do modulate, unevenly, if I am set at Level 4, and also Level 4 is fine for running the bath where the flow rate is quite a bit more (and the odd burner cut out doesn't matter).

Yes, I've looked at the install guide for the WB and it shows a cylinder.

As mentioned in another post I may have misunderstood what the engineer said. A golfing mate was having a new boiler installed and I asked who it was and got him in. This was a month or so back and the mate's boiler had failed totally so there was a two/three day lag before the installation could complete. I suspect the engineer was telling me that as he had done a chemical clean on my boiler it would suffice, and I assume, and will check, that means he only has to drain. refill and recondition the water. The install guide suggests either a power flush or a chemical clean.

Again I may have misunderstood. But then I'm not sure why he even mentioned the issue.

The screw goes into the back of the radiator. I assume there is no valve, either the screw is in tight or air/water dribbles out as it is loosened, taking great care for it to not drop out altogether.

They are awkward shapes to measure. Inlet to inlet? Flange to flange.

I might have to look at this more closely but suspect I might be chasing diminishing returns. The WB boiler has an add-on accessory to attach to the Weather compensation connector on the control panel.

The Drayton Wiser hub can be set to anticipate the temperature (via weather forecasts on the internet), and thus either:

1) In Comfort Mode attempt to ensure the set temperature is reached by the time the control is set. eg if the room is at 16degC and 18degC is called for at 0800, but it is cold, the boiler might kick off at 0700 to try and get to 18degC by 0800.

2) In Eco Mode the boiler will close turn off/down if the weather indicates that the room temperature will still be maintained as it is warming up outside.

I'm in danger of overthinking this. But some good points to go through before choosing the boiler and the installer.

[AnthonyL]

It seems that a chemical clean plus drain is also sufficient. Refer BS 7593:2019

I'll be confirming with the installer.

I'm minded to do that for all the radiators, not least because I can replace and lubricate all the bleed screws.

[Owain Lastname]

I'm getting used to it. Would usually have the lounge at 17 when I had a home of my own.

The bathroom, which is colder, is decidedly a bit nippy and the rechargeable toothbrush batteries don't like the low temperature.

Owain

[Tim+]

Owain never said that was a desirable temperature.

Tim

[Tim+]

Well that’s just part of the joy of combi boilers! Get a hot water tank, you know it makes sense. ;-)

Tim

[The Natural Philosopher]

Yes, and oddly enough, you can drive them from a combi as well.

[John Rumm]

You can test that by leaving a hot tap on the basin running while having a shower. If it does not cut out then, you know it is related to lack of flow rate.

Normally a NTC thermistor in a box you put on an exterior north facing wall.

Depending on the paint thickness that could be 15mm or imperial 1/2" (the latter has a slightly larger OD - although with some persuasion you can normally get a 15mm fitting on it.

Rad tail fittings are normally tapered, and so seal on the threads. Hence the copious PTFE.

With weather compensation and a smarter stat (i.e. one that communicants actual room temp and required temp to the boiler rather than just heat / no heat) a weather compensating system can boost flow temp at times where there is a larger gap between required and actual temp - making the house warm up faster (i.e. it makes the stat work like many people think a stat works - turn it up higher and it *will* make the room get warm sooner :-) )

[John Rumm]

< 1.5 lpm in the winter!

< It is the norm to have a

Hot water circulation works ok if you have a cylinder of hot water and a well insulated pipe run - you just circulate water back to another tapping on the cylinder, so you don't waste much heat, but eliminate delay at the tap since there is hot water right next to it when you need it. Not sure how you would do it with a combi.

[John Rumm]

For a combi you sizing is driven by the DHW requirement. If you are mainly using showers, then a 24kW boiler will do one decent shower (10 lpm winter, approaching 14 lpm summer) at (close to) mains pressure without any problem. If you can find one with a large turn down ration (i.e. wide modulation range) then that would work well enough in anything but a super insulated place)

[RJH]

+1 - I was surprised how much muck remains even after a flush

[AnthonyL]

I wonder whether such a device exists. In the summer my wife is fine with the water from the cold water tap sor washing up. I suspect she prefers it.

At our last coal heated house the enhanced back boiler supplied heat via coils to the upstairs hot water tank, which also had an electric thermostat. In the winter the tank, left to the heat from the fire alone, was never icy cold and usually tepid.

What would work, subject to regulations, would be for a small tank in the loft above the kitchen through which the CH pipes went.