Replacement boiler survey

[AnthonyL]

As posted on here more than once I have an ageing Baxi 105HE combi boiler which is prone to error messages.

Armed with information gleaned from the postings I thought I knew what I would ask the engineer when he came round.

The property is a bungalow with side garage extended into a utility room to the back, and at the end of that resides the boiler. When built the original boilers were installed in the loft space and a hot water tank in the bathroom below.

1) Engineer measured the distance from the gas meter which is near the front of the house and said it may well be too far for the existing pipes. The proposed Worcester Bosch (and he implicated modern boilers) do not take kindly to low pressure. So checking the loft for where the gas pipe runs to the back he thinks, subject to checking, that an increase bore will be required.

I didn't ask but surely there is a ready way to measure the pressure at the boiler? Does all this sound reasonable?

2) The condensate pipe, plastic, runs to the outside and then back in to connect to the utility rooms sink drains. Apparently the bore of that is also too small and if going outside it will need lagging. I suppose I don't know if it has ever frozen.

An option is to run the larger bore pipe inside but silly me assumed that they would have connected to the existing pipe.

So is the engineer being fussy or thorough?

3) He sensibly suggested I await the new install before deciding any of the existing radiators were underperforming. A cold flush would be done through each radiator in turn with the new boiler installed.

4) At first he said to use the WB thermostat system. This apparently used Bluetooth to connect to the room thermostat. I certainly can't get WiFi from the boiler to the slightly near router.

I showed him my existing setup which is a Drayton Wiser hub, in the pantry near the gas meter and is hardwired to the boiler (with thanks to John Rumm) and connects to the battery operated room thermostat via Zigbee and then all operated by an app on the smartphone. He acknowledge this was more sophisticated than the WB offering and would look at removing that from the pack price.

It seems that I'm going to have to wait a couple of weeks for the quote. The company, Worcester Bosch accredited, has good reviews, about a dozen engineers so not a "one man band". They do commercial properties and schools as well as domestic.

I guess that means it's going to cost more but potentially a more professional job.

Comments and guidance on any of the above welcomed.

[alan_m]

Or just do the correct calculations

Page 9 onwards of

Regulations to pipe size have probably changed

How is he going to correctly size or select the new boiler if he doesn't calculate the house heat loss and if the current radiators are adequate? Is he just going to oversize the boiler and possibly leave you with an inefficient system.

Does the WB thermostat and control offer more than your wiser control? For instance weather compensation where the feed temperature of the boiler is adjusted dependant on outside temperature.

>

[Fredxx]

This may be useful too:

No, but Gas Safe assume the quality of fitters has deteriorated and they must use 22mm to a Combi boiler. Saves mistakes in simple arithmetic.

Combis are generally specced on DHW flow rate and are almost invariably oversized.

It may be wireless but don't think it's Bluetooth.

I would expect so.

[John Rumm]

There is - although that can be complicated if there are other gas appliances. Then you would need to make sure that each are running at full demand when you do the test.

It would be instructive to do the sums yourself to see how near (or far) you are from a theoretically satisfactory pipe setup at the moment (using the demand of the proposed new boiler for the calcs)

For a tutorial, see here:

If you know the specs of the boiler, you can translate the input power to a flow volume of gas using this:

(or the installer's manual (usually available on the makers web site) will probably tell you directly.

One would normally run the 21mm pipe to a larger internal drain point before it goes outside. If you need to take it outside sooner, then you should transition to a larger pipe first. The boilers tend to deposit condensate in batches (using a siphonic action like a flush mechanism in a toilet cistern) - that mitigates the risk of freezing a bit since you are not slowly trickling a small volume of water through continuously. However in extreme situations it can still freeze.

The latter arguably.

Even if he suspected that it would work on the current pipework, he would be taking a risk (in many senses) installing it if it was not up to the manufacturers required spec.

A full flush before the new boiler in place is preferable - no danger of pushing contaminants into a new boiler.

Hopefully he quoted for a decent cyclonic and magnetic filter unit on the return before the boiler (if not already fitted)?

Probably a good sign.

Possibly :-)

[alan_m]

That's been the problem in the past - specify the boiler for domestic hot water but ignore what is required for central heating where most of the cost of the gas will be spent.

The boiler should also be selected for CH requirements so, say, specify

25kW for DHW but then ensure that the boiler can also modulate down to maybe 2kW so it doesn't continuously short cycle for most of the heating season, especially if the flow temperature can be reduced to operate the boiler more in the condensing mode.

[Andy Burns]

Dad had his boiler replaced by British Gas, the fitter insisted it needed a new 22mm supply. Dad (who used to work for British Gas) did the calculations to prove the existing 15mm supply was OK.

[alan_m]

From what I've read and viewed over the past couple of years the industry is not full of the brightest of people and often just saying that the gas feed pipe size needs to be larger or the boiler oversized is because they don't know how to do the fairly simple calculations.

It's possibly safer for an organisation to tell their fitters when finding longish runs of 15mm feed pipes to change them for something larger rather than letting the fitters make the decision.

[David]

<SNIP>

<SNIP>

Our current combi was specced to run 2 showers at the same time, so is well oversized as a CH boiler.

You have to take the biggest requirement for heat and then hope this doesn't cause too many problems for other functions.

Cheers

Dave R

[alan_m]

Rather than just hoping why not undertake some basic research into the specification of various boilers and select a combi that can modulate down for CH to a sensible output.

[John Rumm]

And do a heat loss estimate for the house so you know what kind of figures you are aiming for:

[Andrew]

All the houses on my estate (1972 - 1978) have 3/4 inch iron from meter, through the screed to the kitchen where a T joint gave a 1/2 inch feed to the cooker point and a capped-off 1/2 inch stub for a gas fridge.

The 3/4 inch run went behind the Baxi bermuda back boiler with a short run of 15mm copper to the boiler.

[Harry Bloomfield Esq]

I did that, last but one boiler swap, latest boiler - there was no discussion.

[Andy Burns]

In Dad's case the replacement was a system boiler, rather than combi, so likely easier to meet requirement?

[AnthonyL]

I really wish I could readily read your posts. I can read every post on this thread (well most threads actually) and even your earlier post here.

Curious as to what it is happens to go Base64 which my text only client does not deal with.

[Andy Burns]

It's an unfortunate habit of Thunderbird to use base64 when replying to some posts, It's not exactly clear what triggers it (some combination of charset=utf-8, encoding=8bit and perhaps actual non-ASCII characters being present) I've never found a way to stop it, I'm surprised Agent can't handle it though.

[Theo]

$ base64 -d art.txt | hexdump -C

00000000 48 61 72 72 79 20 42 6c 6f 6f 6d 66 69 65 6c 64 |Harry Bloomfield| 00000010 20 45 73 71 20 77 72 6f 74 65 3a 0d 0a 0d 0a 3e | Esq wrote:....>| 00000020 20 41 6e 64 79 20 42 75 72 6e 73 20 77 72 6f 74 | Andy Burns wrot| 00000030 65 3a 0d 0a 3e 0d 0a 3e 3e 20 44 61 64 20 68 61 |e:..>..>> Dad ha| 00000040 64 20 68 69 73 20 62 6f 69 6c 65 72 20 72 65 70 |d his boiler rep| 00000050 6c 61 63 65 64 20 62 79 20 42 72 69 74 69 73 68 |laced by British| 00000060 20 47 61 73 2c 20 74 68 65 20 66 69 74 74 65 72 | Gas, the fitter| 00000070 20 69 6e 73 69 73 74 65 64 20 69 74 20 0d 0a 3e | insisted it ..>| 00000080 3e 20 6e 65 65 64 65 64 20 61 20 6e 65 77 20 32 |> needed a new 2| 00000090 32 6d 6d 20 73 75 70 70 6c 79 2e c2 a0 20 44 61 |2mm supply... Da| 000000a0 64 20 28 77 68 6f 20 75 73 65 64 20 74 6f 20 77 |d (who used to w| 000000b0 6f 72 6b 20 66 6f 72 20 42 72 69 74 69 73 68 20 |ork for British | 000000c0 47 61 73 29 20 64 69 64 20 0d 0a 3e 3e 20 74 68 |Gas) did ..>> th| 000000d0 65 20 63 61 6c 63 75 6c 61 74 69 6f 6e 73 20 74 |e calculations t| 000000e0 6f 20 70 72 6f 76 65 20 74 68 65 20 65 78 69 73 |o prove the exis| 000000f0 74 69 6e 67 20 31 35 6d 6d 20 73 75 70 70 6c 79 |ting 15mm supply| 00000100 20 77 61 73 20 4f 4b 2e 0d 0a 3e 20 0d 0a 3e 20 | was OK...> ..> | 00000110 49 20 64 69 64 20 74 68 61 74 2c 20 6c 61 73 74 |I did that, last| 00000120 20 62 75 74 20 6f 6e 65 20 62 6f 69 6c 65 72 20 | but one boiler | 00000130 73 77 61 70 2c 20 6c 61 74 65 73 74 20 62 6f 69 |swap, latest boi| 00000140 6c 65 72 20 2d 20 74 68 65 72 65 20 77 61 73 20 |ler - there was | 00000150 6e 6f 20 0d 0a 3e 20 64 69 73 63 75 73 73 69 6f |no ..> discussio| 00000160 6e 2e 0d 0a 0d 0a 49 6e 20 44 61 64 27 73 20 63 |n.....In Dad's c| 00000170 61 73 65 20 74 68 65 20 72 65 70 6c 61 63 65 6d |ase the replacem| 00000180 65 6e 74 20 77 61 73 20 61 20 73 79 73 74 65 6d |ent was a system| 00000190 20 62 6f 69 6c 65 72 2c 20 72 61 74 68 65 72 20 | boiler, rather | 000001a0 74 68 61 6e 20 63 6f 6d 62 69 2c 20 73 6f 20 0d |than combi, so .| 000001b0 0a 6c 69 6b 65 6c 79 20 65 61 73 69 65 72 20 74 |.likely easier t| 000001c0 6f 20 6d 65 65 74 20 72 65 71 75 69 72 65 6d 65 |o meet requireme| 000001d0 6e 74 3f 0d 0a |nt?..| 000001d5

It seems like you're trying to send CR LF line endings, and I think Usenet should only use LF. That's probably why TB is encoding it.

Are you composing articles in an external editor maybe?

Theo

[Theo]

Oh actually, there's a 'c2 a0' at 0x9b. U+C2A0 is apparently a 'HANGUL SYLLABLE SYUK' but it's more likely to be UTF-8 for U+00A0 which is non breaking space.

Strange that it decides to encode the CR LF as well though.

Theo

[Andy Burns]

You're right that thunderbird is using CRLF, and that that's not proper, but I'm not doing anything to force the CRs, and I've not found a way to stop it :-(

No, just the built-in composer.

[Andy Burns]

Yes, all stuff I've noticed when looking into the problem when other people have complained about it elsewhere, I think it is a NBSP, but I can't seem to stop it ...

[AnthonyL]

I'm one who has previously raised the problem with your posts. I'm sure I must be reading other posts composed in Thunderbird without issue.

My Agent pre-dates this millenium :) Usenet is/was still supposed to be 7-bit until google groups? or similar messed it up. There is no reason for it to be otherwise and I saw no reason to go from the free to the later paid version. I don't like Thunderbird for Usenet, fine for email, and I don't like systems that require scoring for me to retain/watch/ignore posts though I do have PAN newsreader on my system. That's probably me just showing my age.

To read one of your recalcitrant posts I paste into Notepad++ and use one of their Mime plugin tools.