Iron pipework and heating

[keatsie]

We have a very old and extremely confusing iron pipework serving our very old commercial boiler. We are just trying to work out what to do regards the boiler and existing heating pipework. The boiler is extremely inefficient and although working burns a considerable amount of gas so we need to think about replacing, the pipework is iron and varies in size from 2 1/2 inch pipe work to 1 inch serving the radiators on a single ring, some of the pipework disappears under groud and appearing in other locations from the ground. We have heating stopcocks that we discovered under the floor, rusted open with the heads mostly rusted to dust, I havent managed to work out the entire system flow yet, its extremely confusing.

Those who are willing to quote are coming back with extremely high costs, and everyone is wanting to run new copper and do away with the iron pipes.

I just wanted to get some opinions from others who have better knowledge than i. Anyone had a boiler replaced from a similar pipework, did you replace the entire system with new pipework or just the boiler? Any reason why we cant retain the existing pipework or is it better to bite the bullet and just replace?

 

[malcolm]

Cast iron pipework has been out of use for a long time, but is has quite a long life. I suspect the boiler people have never used it before which is why they want to replace it, or see a big old house and assume you have money (even though a big old house means the opposite). You can buy adapters to screw a copper pipe to an iron one, so it ought to be possible to make a couple of connections to the existing system and then make all of the new pipe immediately around the boiler in copper.

Modern condensing boilers have a much shorter life than big ancient ones, perhaps 10 years so you will get a chance again to replace the rest of the system, but will probably save 20% on bills. The internal heat exchangers tend to be aluminium so a good wash out of the old radiators and pipes first, a magnetic filter in the system beside the boiler, and inhibitor in the system is a must. Otherwise they can start boiling. Ours was installed in 2011 into an existing system with 30 or 40 year old radiators and still seems fine. There are a few new looking pipes around the boiler but the rest of the system is old.

If you did decide to replace the pipes then look into adding independent zones for downstairs and upstairs heating. It saves a fair bit of money not heating upstairs during the day or downstairs during the night. There is some advantage in living in a place over a full winter before deciding on a heating system and zones and things. It is also good to research and ask around when faced with huge bills as most of the time there is a better option. Just replacing elderly thermostats with modern digital room controllers saved me a lot of money. Oh and if you do have everything replaced quality valves are not much more expensive than the cheap ones they will tend to use so insist on them.

 

[88v8]

Single ring?
So no flow and return, just connected to each rad in series, with the water getting colder as it goes through each rad so the rads at the far end of the system need to be huge because there's not much heat left. ??
And no pump?

Not ideal. You can't put thermostatic valves on the rads because that would shut down the whole system.
And expensive to install such a system, unnecessarily big rads.

But it's installed and you didn't pay for it.
So if it works, and each room is getting pretty much the heat it needs, I'd leave it. Apart from anything else, it's 'period' especially if the rads are cast iron.

One thing I would change though... if it's a direct cylinder. I'd change that right away because it means no water treatment is possible and unless you're lucky enough to have soft water the system will be furring up and rusting internally.
Or may already have done so in which case it will be gallopingly inefficient because the boiler will be trying to heat through scale. In which case I'd try a hot descale, but not until next spring, because removing the scale might make the whole thing leak like a sieve and then you're f***ed.

Otoh if you do have soft water then you're laughing. Just fit an indirect cylinder with the appropriate piping mods so you can control the domestic hot water temperature, fit a new boiler, fill it up with water treatment before you fire the new boiler for the first time, and leave it all alone until you win the Lottery.

If the worst comes to the worst, it's not hard to design and install your own heating. Nanny says it's daaangerous to connect the gas, so you'd have to pay some goon to do that for you, otherwise it's just a bit tedious, the design, the plumbing, designing and wiring the control system. I've done it twice, each time using iron rads because I like them and won't put anything modern in a Period house.

Ivor

 

[plasticpigeon]

I agree, a single ring is a stupid system, radiators in parallel with a feed and return is a much better way, and then radiators can have individual control. I think I would go for new pipes in your position, but I'd be wanting to keep any cast iron radiators.

 

[keatsie]

Single ring?
So no flow and return, just connected to each rad in series, with the water getting colder as it goes through each rad so the rads at the far end of the system need to be huge because there's not much heat left. ??
And no pump?

Not ideal. You can't put thermostatic valves on the rads because that would shut down the whole system.
And expensive to install such a system, unnecessarily big rads.

I will upload a couple of photos, the radiators seem to tap into the ring so it is possible to fit thermostatic valves, it also has an inline pump and all the radiators get extremely hot - it is extremely quirky but it does seem to work, just very expensive at 3 hours per day it works out at over £600 per month in gas.

Photos to follow..

 

[keatsie]

Ok, we have a mixture of radiators that are in line and some that tap of the ring, some are modern ish and others are cast iron.

 

[keatsie]

Its a real mixed system... We have updated the timer from an old steampunk AMF venner to a modern electric single channel timer, removed the broken room stat and tmer unit for a modern room stat.

So heating comes on and goes off, radiators work although we have some leaks fom the valves.

 

[MatthewC]

it does seem to work, just very expensive at 3 hours per day it works out at over £600 per month in gas.

That IS a lot unless you live in a mansion!

In the quite large Grade 1 listed church here we had a system much like yours (no thermostats on cast iron rads) but the old pump tripped out when the timer tried to switch it on. The result was that it was on continuously from October to April at a low setting, and the bill for each of those seven months was £1,200 - £1,500 per month! Whilst this is more than double your bill, I would say that yours sounds ever so expensive for a mere house. In 2014 we installed in the church a new boiler (with programmable thermostat and new pumps and filters) which was fed into the old 2.5" iron system and a bit of new UFH. The result was that in the year Aug 14 to July 15 the total bill was (just) £3998 which is £570 per month of use. Hence I would suggest at the very least you need a new boiler urgently with a room thermostat.

 

[88v8]

Ok, we have a mixture of radiators that are in line and some that tap of the ring, some are modern ish and others are cast iron.

So is there a separate flow and return? In other words, two parallel pipe circuits?
Or just a single loop?

That pipe arrangement on the first rad, top & bottom opposite ends, is a classic old-style layout, and btw the most efficient. Much better than the modern arrangement of bottom both ends.

You may need to tighten or repack the valve glands. I used to go round ours every year and see if they needed nipping up.

How is your water heated? Are there are any controls or is the water just at the boiler temp?

Under the floors and around the boiler, are the pipes well lagged? Large unlagged pipes can lose a heck of a lot of heat.

Ivor

 

[keatsie]

Ivor,

Just one single loop, so some of the radiators are in series with the flow others in tap in and are parrelle. I appreciate the descriptions pretty vague, its difficult to describe. All the radiators tap in at the top and out at the bottom, all the valves leak and i have been repacking where possible. A few just started to flood once touched and will need replacing.

I have quite a bit of re-lagging to do, some of the pipes are just warpped in cloth, some in very old lagging while others have poor fitting newer lagging.

The boiler is huge, it has its own room and the pictured don't do it justice.

 

[Flyfisher]

It sounds very similar to the old (and non-functioning when we took it on) system installed in our house, which included a separate 'lean-to' outbuilding for the huge boiler. The outbuilding was demolished sometime in the 80s and the boiler removed but the 2.5 inch pipework and some original cast-iron radiators were still in place. None of the pipework was lagged (except in the attic - and very dubious 'stuff' it was too) and I reckon that it must have acted as quite a 'radiator' in its own right! The radiators nearest to the boiler house look ridiculously small for the size of the rooms and the ones furthest away are very substantial and were a real struggle to remove even with two people and a 'dolly'.

It might have been a more difficult decision if the system had been fully intact and working but in the condition it was there seemed little point in trying to rebuild a very inefficient system so we chose to install a new system. I certainly wouldn't relish £600 monthly gas bills!

 

[bennoa1]

We've had a biomass boiler for nearly 2 years now heating a 2300 sq ft property which is 350+ years old with single glazing and currently almost no insulation other than the roof space, and we're spending around £1500 per annum on pellets per annum which provides water and heat. We've got 13 cast iron school rads which I've refurbed myself - the fitter did a flush after they'd been fitted and he said the system was cleaner than most systems he'd flushed so must have done a good job. Also getting a good slug back via RHI off the govt which should cover the initial fitment plus around 10 years of fuel!!

 

[malcolm]

£600/month seems a lot. Is that averaged over the year? I've been maxing on about £250/month over the coldest months of winter and over the year around £1100 total. I'm not sure of the area that is heated, maybe 200m2, solid walls and single glazed currently. The national average is supposed to be around £500/year.

It does sound like replacing the pipework could improve the efficiency of the system. I would plan it out carefully using multiple zones and room controllers. My controllers are Danfoss TP9000 which allow different temperatures to be set at different times of the day. I have 3 heating zones - upstairs, then different areas of downstairs allowing the heat to be reduced when the area is not in use, and a little area downstairs to be more cosy than the rest. Originally the system had bi-metallic strip thermostats which switched on at about 12C and off at about 25C, and the horrible times that make it cold when they are off.

No harm replacing the boiler first then doing the pipework when you have other major work to do. I suppose if the boiler is old and silted up it probably won't be running at the efficiency it once did. Those big old things will be around 65% efficient or less. A modern condensing boiler would be around 95% efficient.

This time of year is a bad time to get quotes. Plumbers tend to be very busy during the heating season.

 

[jocelyn plummer]

I can vouch for the success of having downstairs and upstairs heating on separate zones. Our 5 bed/4 reception house in Ampthill was heated by 16 radiators , and as I was in a position to take out and replace the entire heating system I separated the zones. It meant warm at night upstairs , and warm in day downstairs, two time clocks and thermostats on every rad meant we had plenty of control, and comfortably cosy.

 

[bennoa1]

We decided to put 2 circuits but front and rear as the front is north facing (and colder) with the rear south facing and gets a good slug of sun warmth. Has worked well.