Designing gas central heating for DIY maintenance.

[epsilonGreedy]

Another thread today got me thinking about the long-term cost of maintaining a gas central heating system which led me to investigate annual contracts to keep a whole central heating system working.

 

£250 to £400 p/a seems like a sensible medium range to base calculations on when assuming £0 per fix excess. Using pension annuity rate tables I reckon for me that would require £15k placed in an annuity to generate a life long indexed linked income to fund comprehensive gas central heating maintenance cover = ouch.

 

I can already hear some well known forumites saying "design out gas". I would counter by saying the long-term maintenance costs of ASHP are an unknown. At this point I can see the whole lifecycle cost advantage of inline electric heaters, running on E7 charging up the heat capacity of a UFH slab, when in stalled in a near passiv standard home i.e. little heating outside the E7 time band. Plus a very cheap install cost.

 

But back to designing a gas central heating system to keep the £££ hungry GasSafe wolves outside the front door.

 

What can be done to aid DIY monitoring, servicing and fixed of gas central heating?

1. @JSHarrismentioned cleaning and swapping inline filters in the water circulation.
2. Another post described a clear glass view port to eyeball clarity of the water.
3. Isolators on all rads.
4. Isolators on all the swappable bits such as the pump and direction valve in the airingcupboard.
5. How about some extra plumbing to make a complete system drain/flush a doddle.
6. What can be done to legally make it simple to conduct an annual pressure test on the gas supply?

 

And finally thinking of extreme measures how about buying a duplicate boiler from the start. This would guarantee the simplest swap out of a boiler at 10 or 15 years and hopefully a cheap quote from a pro for the job. In my experience the maintenance costs mount up beyond 8 years as each component failure requires two visits, one to diagnose and another to replace. Such a bill is typically £150 for labour plus £100 for the part.

Edited October 4, 2019 by epsilonGreedy

[PeterW]

13 minutes ago, epsilonGreedy said:

What can be done to aid DIY monitoring, servicing and fixed of gas central heating?

1. @JSHarrismentioned cleaning and swapping inline filters in the water circulation.
2. Another post described a clear glass view port to eyeball clarity of the water.
3. Isolators on all rads.
4. Isolators on all the swappable bits such as the pump and direction valve in the airingcupboard.
5. How about someth extra plumbing to make a complete system drain/flush a doddle.
6. What can be done to legally make it simple to conduct an annual pressure test on the gas supply?

 

1. A magnetic filter / cleaner is a requirement on most if not all new boilers

2. Pointless - use the drain on the mag filter (see 1)

3. You do anyway. 

4. Pumps are fitted with valves. Adding 3 full bore valves around a diverter would be different ...

5. It’s there already - use a drain point valve on the utility radiator/ lowest rad. System already should have a filling loop to refill. 

6. Nothing. Nada. Nowt. It’s illegal, don’t go there. 

 

 

[ProDave]

If the annual servicing cost is likely to be £250 or more, then on a low energy house that has got to be very close to the annual heating bill.  It starts getting silly when the cost of servicing something doubles your cost of using it.

 

So I would be designing out gas and using something like an air source heat pump. No annual service cost, no standing charge to pay for gas, and all that saving will likely pay for most of the electricity it uses.  If you really like gas cooking then an LPG fired hop running from 47Kg cylinders.

 

But on the subject of servicability.  There are some makes of brass pump connector that have an isolator built in.  Waste of time.  When a pump in our old house failed so too had the isolators, so it was a partial drain down anyway to replace the pump and the connectors.  Perhaps separate full bore in line isolators and a simple pump connector.

 

Trying to fix a problem for a neighbour at the moment, the BEST thing you can do to aid maintenance is keep a clear and accurate diagram of how the system is piped, and WHERE the pipes go, with photographs of pipework before the floor or ceilings go down.  And pass this file of information on if you sell the house.  Then you won't be cutting random holes in the ceiling hoping to find the leaking pipe (don't assume the leaking pipe is above where it is dripping)

 

Motorised valves.  I would only fit Honeywell now. Too many of the "plastic" ones have common faults with microswitches.  It is rare to have to change the valve body. The actuator head can be changed if it fails with no plumbing.

[epsilonGreedy]

7 minutes ago, ProDave said:

If the annual servicing cost is likely to be £250 or more, then on a low energy house that has got to be very close to the annual heating bill.  It starts getting silly when the cost of servicing something doubles your cost of using it.

 

 

Agreed about the sillyness.

 

The £250 is for a first-year fix any number of problem at zero cost contract with British Gas. Apparently annual increments often push this up to £400 as the computer algorithm gets to know how wonky your central heating system is. Cases mentioned in the papers cite £700 annual renewal premiums which I assume is BG's way of saying, we have had enough time to fit a new boiler.

 

The £250 level figure is justified in the marketing on the basis that an annual service is going to cost £90 regardless and this is included with the £250 annual cover.

[epsilonGreedy]

33 minutes ago, PeterW said:

 6. Nothing. Nada. Nowt. It’s illegal, don’t go there. 

 

 

I was thinking more about installation features that would persuade a pro to lower his regular service fee because a self builder's central heating installation was very easy to work on.

[PeterW]

1 minute ago, epsilonGreedy said:

 

I was thinking more about installation features that would persuade a pro to lower his regular service fee because a self builder's central heating installation was very easy to work on.

 

Ahhh

 

then don’t box it in, don’t stick it in a corner and make sure there is 300mm clear all round. 

[SteamyTea]

7 minutes ago, PeterW said:

then don’t box it in, don’t stick it in a corner and make sure there is 300mm clear all round. 

Why not fit the boiler to externally in a suitable wind and weather proof box?

[PeterW]

Just now, SteamyTea said:

Why not fit the boiler to externally in a suitable wind and weather proof box?

 

Haven’t seen a gas boiler suitable for external mounting. There are boilerhouse models, but most if not all need to be somewhere above 5c at all times.  

[joe90]

1 hour ago, epsilonGreedy said:

. I would counter by saying the long-term maintenance costs of ASHP are an unknown.

 

But most of the ASHP,s are built by large manufacturers such as Carrier (like mine) who have been building air con systems (ASHP in reverse) since 1902, it’s just a fridge in reverse and how often does a fridge go wrong or need a service?

[Conor]

Don't know what you guys get for £250-£400 pa, but my last boiler service was £40. And you don't HAVE to do it every year, it's not like the boiler police call round and do inspections.

[joe90]

I have to get the boiler in our rental serviced annually (£45) and I know the boiler is old and spares difficult to get but I took out direct line landlord insurance and it covers boiler breakdown and even boiler replacement if spares are not available ?

[oldkettle]

Last time we installed WB it came with 7 year warranty. We paid about £2K, this is SE, and we had not much choice as the old boiler packed up in winter. But after that we paid 70-80 for the service by the same certified WB installer. So even if we assume a new one is required after 7 years (which is highly unlikely) the overall cost per year will be (2000+80*6)/7<360. I suspect in reality it is a bit lower. Now, was your number above for maintenance only or for the whole thing, @epsilonGreedy?  

Edited October 4, 2019 by oldkettle

[Temp]

7. Make it easy to put corrosion inhibitor in the system !

 

I seem to be banging on about corrosion inhibitor at the moment. Must be the time of year.

 

I'm sceptical of annual maintenance contracts. They cover servicing but most do NOT include checking or topping up the corrosion inhibitor. Yet this is the most important thing you can do to keep your system reliable. Without it over time sludge builds up and can block pipes and pumps and cause leaks in the boiler and rads. The first you know about it is the system fails to work when you switch on the heating in September/October. The sludge has settled out over summer and blocked a pipe. When the service man rocks up he tells you the contract doesn't cover the first power flush. You are faced with a bill of £300-£800. Sometimes they tell you its mandatory to have one or they won't cover you any more. You can shop around and get a power flush done by another company but there are quite a few sharks out there.

 

Adding corrosion inhibitor like Fernox F1 can help prevent the problem...

 

If your system is vented you can just tip a bottle or three into the header tank but this can mean a climb into the loft.

 

If your system is pressurised you have to lower the pressure and use a kit to inject the stuff into a radiator bleed valve or similar. Then repressurise the system.  This would be a lot easier if there was a "filling port". See my next post in a moment.

[PeterW]

2 minutes ago, Temp said:

This would be a lot easier if there was a "filling port". See my next post in a moment.

 

Mine has one - called the Mag Filter. Can empty it, then it takes 500ml bottles of inhibitor. 

[Temp]

There might be an easier way but here is my idea for a filling port for pressurised systems. To add inhibitor you would switch off the system and close valves A and B. Then open C and D to drain the 1L tank. Then close D and pour inhibitor into the tank via the funnel. Then close C and reopen A and B. Switch system back on.

 

[Jeremy Harris]

Our old system was dead easy to top up the inhibitor, via the mag filter.  I used to just fill the filter chamber up with neat inhibitor after cleaning it.  Not sure what the concentration was, but as it was a closed and pressurised system I reckoned a filter full should have been enough to keep it working OK.  The mag filter was dead easy to clean, too, just close the two isolating valves, stick a bowl underneath to catch any spillage and whip it off for a clean.

[epsilonGreedy]

32 minutes ago, Conor said:

Don't know what you guys get for £250-£400 pa, but my last boiler service was £40.

 

 

The £250 is for a comprehensive warranty that British Gas will keep your boiler and central heating running no matter how many bits fail.

[PeterW]

But rads don’t fail like they used to anymore. The biggest issue is rust and crap in the system and old header tanks used to be the big cause of that as oxygenated water gets in. 

 

Fit decent rads in the first place, don’t use B&Q specials. Then decent levels of inhibitor and a good mag filter, preferably with a strainer too. Plastic pipe also helps as there is less corrosion / galvanic action with less copper in the system. 

 

These filters are pretty good and not expensive. Also have a stainless gauze in them to trap bits of non-magnetic crud. 

 

And pick a boiler with a stainless heat exchanger with a decent warranty and you should have no problems. 

 

 

[Jeremy Harris]

1 minute ago, epsilonGreedy said:

 

The £250 is for a comprehensive warranty that British Gas will keep your boiler and central heating running no matter how many bits fail.

 

 

I think it's worth looking at whether this is good value or not.  I suspect it's not.  We fitted a Vaillant combi at our old house, probably in around 2006 or thereabouts.  We had major problems with the thing for the first year, which turned out to be installation related.  After that it was pretty reliable.  The diverter valve failed after about 6 years or so, but was replaced for around £130.  Services tended to be around £70 to £80, but included a safety check on the gas cooker and gas fire.  We didn't get it serviced every year, probably every two or three years or so.

 

I think the secret is finding a good local plumber who doesn't charge an arm and a leg.  We found one when we were having problems following the installation (the installers were complete numpties) and as his prices were OK and his service good we stuck with him.  At a guess I'd say that over the 12 to 13 years we ran that boiler it probably cost us around £40 a year in maintenance and repairs.  Not a lot really, and significantly better than paying BG £250 a year.

[epsilonGreedy]

47 minutes ago, oldkettle said:

So even if we assume a new one is required after 7 years (which is highly unlikely) the overall cost per year will be (2000+80*6)/7<360. I suspect in reality it is a bit lower. Now, was your number above for maintenance only or for the whole thing, @epsilonGreedy?  

 

 

It is a keep it running type contract not matter how many visits and parts.

 

Your < £360 p/a figure based on a replacement cycle indirectly validates that these other contracts are within the realms of reasonable.

[PeterW]

6 minutes ago, epsilonGreedy said:

Your < £360 p/a figure based on a replacement cycle indirectly validates that these other contracts are within the realms of reasonable.

 

Not really as BG will get to a point of charging you £2200 for a new boiler at some point. So that’s a TCO value at £360 p/a inc write off.

 

Yours is £350 p/a plus additional boiler so would be £650 p/a...

[oldkettle]

9 minutes ago, epsilonGreedy said:

 

It is a keep it running type contract not matter how many visits and parts.

 

Your < £360 p/a figure based on a replacement cycle indirectly validates that these other contracts are within the realms of reasonable.

 

But do these maintenance contracts include free boiler replacement? I doubt it which means - as said by others - they are not particularly good value. 

 

Edited to add: I also look at it differently. My gas bill at the moment is well over £600, so even 360 extra don't sound too bad. Agree, that when I retire it won't be that easy. 

Edited October 4, 2019 by oldkettle
Clarification

[epsilonGreedy]

1 hour ago, JSHarris said:

At a guess I'd say that over the 12 to 13 years we ran that boiler it probably cost us around £40 a year in maintenance and repairs.  Not a lot really, and significantly better than paying BG £250 a year.

 

 

I think you have found the sweet spot, with replacement every 10 to 15 years. I reckon the nightmare for many starts with a succession of bills in the £100 to £300 range, not enough money to spring £2000 on a new install hence they get locked into a £250 per year maintenance contract.

 

Having thought about the situation today I reckon the sensible midway DIY path is to learn everything to do with central heating maintenance outside of the legal restrictions on the boiler. Keep a spare pump and diverter valve on hand for quick DIY replacement. Do routine filter and inhibitor treatments on a diy basis and then intermittent servicing visits from a pro. Having witnessed one service at my house I think I am capable of looking at the flame burn once a year and just like the visiting CORGI pro, saying "yup nice consistent clean blue fame burn there".

Edited October 4, 2019 by epsilonGreedy

[Big Jimbo]

I would defo say, inhibiter, inhibiter, inhibiter. I fitted a boiler about 15 years ago (with the exception of the gas connection) because i was doing the whole house up, one room at a time, i knew i would have to keep draining the system. I thought, being a tight git, that every time i drained to do another room, i was going to loose all my inhibiter, so thought i would wait untill i did the last room to add it. 12 months later boiler packed up. Heat exchanger totally blocked due to not having any inhibiter in it for the last year. DOH.

[Big Jimbo]

Now im not a plumber, but have done central heating in my own houses, and my 3 daughters houses.

I always fit a magnatec or equiv.

I did my own house in a mixture of plastic and made use of some of the existing copper. Then i put ply all over my ground floor, and tiled it. 3 years later i had a plastic pipe pop out of a plastic conc.........As you can imagine. Nightmare.

Daughters house. I did it all in copper, which was expensive, and a pain getting through joists etc. However, never had a prob in 7 years

2nd Daughters house. I did it all in plastic, but without a single joint under any floor. Basically, I ran a flow and return pipe to each rad, and made up a manifold (under the stairs) Full bore isolator on each flow and return, so i can isolate, and remove any rad at any time. And even keep the heating on. Did the same upstairs. Been in 2 1/2 years and works a treat.