Upgrade of old plumbing system, Solid Fuel Rayburn, Well Water, Oil boiler

[Iceverge]

I'm proposing to do something about the water system in my parents house. 

 

The system as currently stands is a mishmash of pipes and systems installed since the house was built in 1951. 

 

Water is provided by a well that is quite acidic, copper cylinders typically only last about 5-10 years. It feeds some of the cold taps directly from the main pipe from the pump and some via a gravity tank in an upstairs bathroom. 

 

Hot water is provided by a 120L direct copper cylinder heated on a gravity loop from a Rayburn 355sfw with a 16Kw boiler. Again distributed via a gravity fed header tank. Central Heating is from a 25 year old Firebird Popular Oil boiler to rads with a header tank in the Attic. 

 

Showering is done by an electric shower fed from the mains. 

 

 

 

Current issues are. 

 

1. The high cost of oil in heating an old house. 

2. The Rayburn is lit "religiously" with free timber daily for cooking and DHW. However the water in the copper cylinder is frequently approaching boiling temp with risk of scalding and damage to taps etc. It has a steel backboiler so water is brown from the hot taps, running DHW directly through the boiler is corroding it also. 

3. The attic needs insulation but as it contains header tanks that may need moving/replacing we're holding fire on that. 

4. The well water corrodes all copper and brass fittings eventually. 

5. The Electric shower forms the vast majority of the electricity bill while most wood heated DHW goes to waste. 

 

 

The ideal system. 

 

1. Have a hybird system that allowed the oil and/or rayburn to provide hot water and heating. 

2. Remove all tanks from the attic. 

3. Replace the current mix of piping with Hep20. 

4. Switch to a pressurised system.

5. Move the cylinder downstairs to free up space for an ensuite upstairs. 

6. Retain the Electric shower. 

 

 

 

My proposal.

 

1.  Bring a new 22mm MDPE pipe directly into the house from the well. 

2. Run it to a cold Hep2O manifold for radial cold water distribution.

3. Install a DHW "coil in tank" thermal store on the ground floor above the level of the Rayburn.

4. Run the Rayburn on a gravity circuit. 

5. Connect the Oil boiler to the store on a pumped circuit. 

6. Connect the existing CH loops to the store and have them operated by a temp switch near the bottom of the tank. 

7. Run Radial hot water  pipes from a new Hep20 Manifold and a thermostatic mixing valve. 

 

 

Issues

1. With a combi tank the thermal store header/expansion would be below the level of the upstairs rads meaning they'd need to be decommissioned. A header tank in the attic could solve this but I like the tidiness of a combi thermal store and consider it safer in a location where all leaks can be drained outside easily.  Also I don't want to have to cut joists (6x2" at 16" cc) to fit a new tank up there. 

2. Thermal stores are harder to get in Ireland then than the UK and may be expensive. 

3. Access to existing pipes etc, (not Buildhubs problem I know) 

4. Infinite funds not available and might need to be completed piecemeal. 

5. What options are there for running primary water loops other than copper. I gather Hep2O/pex isn't an option however copper would be very hard to retrofit. 

 

 

Please critique my plans. 

 

 

 

 

 

[Iceverge]

Any takers? 

 

At least is Multilayer PEX-Al-PEX suitable for taking water from an oil boiler to a thermal store? 

 

 

[markocosic]

I'd plunder the Thermal Integration designs for ideas:

 

https://www.heatweb.co.uk/hot-water-storage/

 

And the continent for hygiene buffers as the like to call them. Putting a 1,000 litre coil-in-tank thermal store on the ground floor is a standard use case. Lower half serves heating and hot water preheat. Upper half serves hot water only. Either gravity circuit to pressurise this and the radiators and the aga; or run coil-in-tank to put heat from the aga (on a small gravity circuit) into the sealed thermal store and radiator circuit.

 

Heat pump is your only other option to reduce oil use. This can heat the bottom of the store when the aga is not is use. Or you can arrange it to heat either the top (to 55c) or the bottom (to whatever degC) of the store with some changeover controls. The big volume will let you follow the sun/follow the pv in summer and ride through cloudy days.

 

Treat the primary water as you fill. Then no need to worry about primary pipework materials.

 

Coilsn for hot water in these tanks will be stainless. Tanks mild steel.

 

[JohnMo]

Issues

 

1. With a combi tank the thermal store header/expansion would be below the level of the upstairs rads meaning they'd need to be decommissioned.

 

Could you run from coil in cylinder, then no issue supplying upstairs rads, just run a pressurised heating system?

[Iceverge]

@markocosic that sounds similar to the idea I had. With thermal stores as I understand it the bigger the better however the only suitable location is 630mm wide hemmed in by block walls. 

 

I could probably fit a 300l one like this. 

 

I'm not aware of any tanks with a stainless steel coil. Where might I find such a unicorn!?

 

Heat pump is beyond the budget and oil boiler is in situ. TBH the wood cooker gets used so frequently that I doubt the oil will be used often at all. 

 

As a distant idea a solar PV divert could be used down the line. 

 

@JohnMo

 

The idea of a pressurised heating system didn't occur to me and am fairly unfamiliar with then. I guess it's just a case of an expansion vessel, and pressure/temp relief valve a filling loop?

 

Alternatively I could make do with the existing attic header tank for the heating with a coil in tank for it I suppose.

 

[Iceverge]

Oh, if anyone has a coil in tank 300l TS at 60deg would it fill a bath? 

 

 

[JohnMo]

10 minutes ago, Iceverge said:

@markocosic

 

@JohnMo

The idea of a pressurised heating system didn't occur to me and am fairly unfamiliar with . I guess it's just a case of an expansion vessel, and pressure/temp relief valve a filling loop?

 

Alternatively I could make do with the existing attic header tank for the heating with a coil in tank for it I suppose.

 

A gas combi boiler uses a pressurised heating loop, as described.  The alternative is your existing header tank.

[markocosic]

Hygiene Pufferspeicher

Hygiene Solarspeicher

 

One steel coil (for heat input from a boiler) and one copper or stainless coil (for the DHW) are fairly common.

 

e.g.

https://www.ebay.co.uk/itm/124306034654

https://www.ebay.co.uk/itm/125426739465

 

Tank (and rads) filled with pressurised, sealed, treated, primary water. Boiler loop into the Rayburn/Aga/Woodstove stays gravity pressurised with the option to safely boil dry if all goes to shit. It can still be pumped (and there's some good sense in using the pump to decide when to heat the storage or not to avoid cooking the storage) but you leave it gravity pressurised / open vented. DHW loop has...DHW in it.

 

Better systems use plate heat exchangers mounted external to a tank with no heat exchanger inside for hot water. These offer tighter control of your outgoing hot water temperature and a smaller deltaT.

 

You need something to ensure stratification within the buffer vessel (to avoid heating water stirring the whole thing into a convection-current mixed mess and your hot water being lukewarm)

 

I would move the walls myself or find a new location to put in a larger tank. (1500 rather than 600 litres)

 

If you don't heat pump this today then make provision in the buffer design / system layout to bolt one on later. Doesn't have to be to replace the oil. Can be an additional.

 

If wood really is free though then why not get something more efficient than a Rayburn/Aga at putting heat into water? 

 

 

Or got the opposite way with a log boiler and a log water heater that are meant for heat-to-rads and heat-to-water?

 

https://www.senukai.lt/p/kietojo-kuro-katilas-kalvis-5-12-12-kw/5r8d?cat=ayf&index=2

https://www.senukai.lt/p/vandens-sildytuvas-ariston-sle-80-3-75-l/3nl7?cat=azr&index=25

 

The latter have DOUBLED in price since Russia invaded Ukraine for what it's worth. Use to be sub €200...

 

https://www.ebay.co.uk/itm/252418071520?hash=item3ac54a1be0:g:WskAAOSwz~paFIpy

 

80 litres is enough to shower. Many come with small immersions (the lithuanian one was 1.2 kW) designed for hokey power supplies but also good for PV diversion.

[Iceverge]

20 hours ago, markocosic said:

Boiler loop into the Rayburn/Aga/Woodstove stays gravity pressurised with the option to safely boil dry if all goes to sh

 

Is there a risk of it overheating and over pressurising the  primary water in the store in the meantime? 

 

20 hours ago, markocosic said:

Better systems use plate heat exchangers mounted external to a tank with no heat exchanger inside for hot water. These offer tighter control of your outgoing hot water temperature and a smaller deltaT.

 

 

These require a pump and a power source as I understand albeit with better utilisation of the volume of the hot water in the store. Also as the house is only 2 occupants for the majority of time the volume issue would be less important vs time of hot water to taps.  A coil in tank would strike me as a better solution in case of a powercut. Rural Ireland here and can sometimes be without electricity for 1-7 days in a storm. 

 

20 hours ago, markocosic said:

I would move the walls myself or find a new location to put in a larger tank. (1500 rather than 600 litres)

 

Not a practical option I'm afraid as the walls are structural and no other easy location exists to house a larger store..... I think....... I'll have another look later. 

20 hours ago, markocosic said:

 

If wood really is free though then why not get something more efficient than a Rayburn/Aga at putting heat into water? 

 

It's used for cloths drying, cooking and company so I think any suggestion of removing it will be vetoed sharpish. 

 

20 hours ago, markocosic said:

 

If you don't heat pump this today then make provision in the buffer design / system layout to bolt one on later. Doesn't have to be to replace the oil. Can be an additional.

 

Good point I suppose it's only a couple of ports. 

 

 

Would this be ok for Primary water to and from the Oil Boiler? Is there any method of reducing mixing in the store when using a pump? 

 

 

 

 

 

 

[dpmiller]

@iceverge you're talking about something very similar to what World Heat made up for me. I've a 270l store with built-in expansion space, DHW coil, ASHP coil, and direct tappings on the tank for the boiler stove.

[Nickfromwales]

OK.

Firstly, only use copper for the primary pipework whatever you do!! No other product is rated for boiling water / steam. That's why the gravity tanks should be galvanised steel, as plastic tanks melt and shower occupants with scalding water. People have been killed by this happening where they got scalded to death in their beds when the tanks just folded in and dropped on them. It's a very serious issue.

On 11/08/2022 at 12:13, Iceverge said:

It has a steel backboiler so water is brown from the hot taps, running DHW directly through the boiler is corroding it also.

These two bodies of water should not be meeting? The heated primary water should be going through a coil? Is this a failed / failing primatic hot water cylinder?

 

On 11/08/2022 at 12:13, Iceverge said:

The high cost of oil in heating an old house. 

Buy lots in the summer, as the cost of this system conversion will not be cheap!!

 

On 11/08/2022 at 12:13, Iceverge said:

Have a hybird system that allowed the oil and/or rayburn to provide hot water and heating. 

Simple to achieve tbh, but the Rayburn will need to a) keep the galv header tank, or b) be garnished with a retrofitted cold mains fed quench valve ( which cools the solid fuel device with mains water ) but that may not be suitable / compliant for an existing device. Also being mindful that your cold mains is power-dependant, so adds another degree of complexity!! I'd just keep the header tanks tbh, renewing them to be sure of longevity / suitability / reliability etc.

The ground floor cylinder could then just be a gravity thermal store, stainless steel to combat corrosion issues as best as possible, and a very simple device where all bodies of primary water are shared, eg your hybrid setup would simply converge there.

 

Where is the current cylinder? In this 630mm wide location or elsewhere? If there is a second cylinder location available, I would go;

• Rayburn > TS
• TS > Space heating
• Oil > Space heating ( ignoring TS when Rayburn is not in operation ) future-proofs against old age / sick days etc.
• Oil > DHW UVC ( when Rayburn not in operation ) "" ditto
• TS > DHW UVC ( when Rayburn is in operation ) doubles up thermal storage capacity to maximise 'stored' heat, eg DHW still ( residually / theoretically ) available early morning before lighting Rayburn

 

On 16/08/2022 at 13:41, Iceverge said:

Good point I suppose it's only a couple of ports. 

This house will never run off a heat pump. Flush that idea from here please!?!

 

On 11/08/2022 at 12:13, Iceverge said:

1. Have a hybird system that allowed the oil and/or rayburn to provide hot water and heating. 

2. Remove all tanks from the attic. 

3. Replace the current mix of piping with Hep20. 

4. Switch to a pressurised system.

5. Move the cylinder downstairs to free up space for an ensuite upstairs. 

6. Retain the Electric shower. 

1. Doable
2. Nope, not for heating anyways. Prob need the keep a CWS from the borehole for reliability. It's an attic, just leave it alone / utilise it to your advantage ( benefit ) imo.
3. Not for the primary heating from solid fuel, copper best for the backbone here afaic.
4. Nope. That means added maintenance for the old-folk, topping up, checking pressures, etc. Will also promote introducing leaks where weak spots currently reside.
5. Poops on my idea for a dual-cylinder arrangement. If this is for the parents to grow old with, consider the en-suite / bedroom arrangement for downstairs maybe?
6. Electric showers are shart on a good day, also not thermostatic unless you upgrade? Mixer showers off the TS or UVC would be far superior, plus pointless having PV diversion if it's going into a dead end whilst grid electricity is chewed up in parallel?? 

OK. Lets start there  

Edited August 17, 2022 by Nickfromwales

[Miek]

I would begin by installing  a water hardner to up the PH. My old house has acidic water from a spring and it destroyed the whole copper pipe system and the water tasted metallic.  The limestone prewash made a huge difference.  

[Iceverge]

Thanks very much all for replying.

 

There's really no excuse for not getting the water sorted. My best mate installs softeners plus treatment units! Must organise a water test asap.

 

15 hours ago, Nickfromwales said:

That's why the gravity tanks should be galvanised steel, as plastic tanks melt and shower occupants with scalding water. People have been killed by this happening where they got scalded to death in their beds when the tanks just folded in and dropped on them. It's a very serious issue.

 

The current one is fibreglass, is that acceptable? Aware of the dangers, I think there was a terrible case somewhere in SW England a few years back I think when a tank came through the ceiling. Hence wanting to do something about it. Also it forms some of my motivation of wanting to keep all stored water downstairs in a tanked cupboard with a drain to outside. 

 

15 hours ago, Nickfromwales said:

These two bodies of water should not be meeting? The heated primary water should be going through a coil? Is this a failed / failing primatic hot water cylinder?

 

It was originally a 1950's system with a copper boiler in the Rayburn where all the DHW water went through the rayburn and a direct cylinder. The swap for a newer (but still 2nd hand) rayburn with a steel boiler last year has caused brown water from the hot taps and no doubt corrosion of the boiler. A bodge that needs fixing. 

 

Is a pressurised heating circuit much more resilient to corrosion etc than an open vented one with a header tank? I'm fond of the idea of a header tank over expansion vessels as a low maintenance system. 

 

Theres an existing W/C with space for a shower if we remove the Copper Cylinder upstairs.  Theres a shower in existence downstairs at them moment and a room that could be a bedroom so thats not a huge concern. 

 

The cupboard downstairs is 630x950mm x 2650mm high. Its adjacent to an external wall with a void in the floor (used for an open fire bellows originally) That could be used for a new feed to the house. Its also directly below the upstairs W/C. The cupboard is 1.5m from the Rayburn laterally and the 3rd wall backs onto a wall where pipes could easily be routed to the oil boiler. It really is ideally placed but just a little tight. 

 

 

Ok how about this.

• Well water > Water softener
• New MDPE pipe routed to direct combi TS + Hep2O cold manifold
• Rayburn > TS
• Oil > TS
• TS > Downstairs Rads only. 
• TS > Blending valve > Hep2O manifold.

 

CH to be operated by Temp switch near the bottom of the TS to ensure that CH doesn't cannibalise DHW. 

 

If CH needed just fire the boiler or Rayburn and once the DHW portion of TS is hot then CH will spring to life. Slower yes but simple and should ensure DHW is protected?

 

The rayburn will defo be copper piped primary to TS. Is there no more flexible option for the primary pipework from the oil Boiler as this will be tricky to route?

 

Oh one more question. Is sludge lightly to banjax the TS connecting it to a set of old Rads and a steel boiler that is rusted internally on the Rayburn?
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Nickfromwales]

5 hours ago, Iceverge said:

The current one is fibreglass, is that acceptable?

Yup, as long as it has a copper overflow and copper ( metal ) connected pipework.

 

5 hours ago, Iceverge said:

It was originally a 1950's system with a copper boiler in the Rayburn where all the DHW water went through the rayburn and a direct cylinder. The swap for a newer (but still 2nd hand) Rayburn with a steel boiler last year has caused brown water from the hot taps and no doubt corrosion of the boiler. A bodge that needs fixing. 

This bit is confusing me. Gravity primary's normally convey heated primary water to a coil in a DHW cylinder, been that way since I was knee-high to a grasshopper. How many tanks are in the attic? 

 

On 11/08/2022 at 12:13, Iceverge said:

The attic needs insulation but as it contains header tanks that may need moving/replacing we're holding fire on that. 

Are these both fibreglass? One for the CH circuit of the Rayburn, and a second exclusively servicing DHW? How many connections ( and where ) on the copper DHW cylinder atm?

Need to understand this a bit better, but tbh mostly out of curiosity if things are to be changed around anyhoo.

 

5 hours ago, Iceverge said:

Is a pressurised heating circuit much more resilient to corrosion etc than an open vented one with a header tank? I'm fond of the idea of a header tank over expansion vessels as a low maintenance system. 

A 'circuit' will be a victim of circumstance, so no generic yes/no there  If a circuit has UFH and stainless / copper parts the corrosion issue is miniscule, if rads are present the issue is increased, albeit still manageable with inhibitors etc. If folk are bathing in DHW from a primatic cylinder you cannot treat the primary water so must upscale on design / diligence, but if your DHW and the CH primary water re two completely separate bodies of water ( suggested by the 'plural' reference to the header tanks ) then there are options for chemically treating the water to better manage condition. A magnetic filter would be an obvious friend to introduce here, but it would need cleaning out regularly for the first year.

You don't really want to introduce a sealed and pressurised setup here, IMHO, as the folks will have to monitor / top up / make sure they don't over-pressurise etc etc, aka ball-ache. F&E = simple life / minimum routine maintenance. If the F&E tanks remain in the attic ( which they very likely will have to ) then you're fine to stay on gravity, so one less problem. Upstairs heating stays on that too so, so happy days.

 

So; 

Bathing still to be off electric showers? Ergo stored DHW will be for washing hands / dishes etc only? Seems madness to me, especially if 'religious' Rayburn usage is on the cards for the foreseeable? Remember that occupancy by anyone deemed infirm requires thermostatic control for anti-scald, so regular electric showers 'should' be changed, for both safety and comfort, ( if being retained ).

 

6 hours ago, Iceverge said:

Ok how about this.

• Well water > Water softener
• New MDPE pipe routed to direct combi TS + Hep2O cold manifold
• Rayburn > TS
• Oil > TS
• TS > Downstairs Rads only. 
• TS > Blending valve > Hep2O manifold.

What will happen the the second heat exchanger connections? The ones doing DHW via the steel tank? Te Rayburn is a 4-pipe setup atm yes? 

[Iceverge]

Sorry for the delay, work were making me work for a change! 

 

I'll have a go at some pics and a sketch later if I can. That will explain all. 

[Iceverge]

Ok, here goes. 

 

The central heating is worked from an oil fired boiler. 

 

 

 

Feeding 5 Rads downstairs and 5 Rads upstairs. 

 

 

It is kept topped up by a Tank in the Attic. 

 

 

 

 

Here's a Sketch of what I think it looks like

 

 

 

[Iceverge]

Right now on to the DHW. 

 

There is a wood fired Rayburn 355SFW model. 

 

 

That feeds a direct copper cylinder via a gravity circuit. 

 

 

 

This in turn is fed by a fiberglass F+E tank. 

 

 

 

 

 

Here is a diagram of what I think is happening. 

 

 

 

Hope that helps clarify where we are. 

 

[Iceverge]

Proposed Upgrade. 

 

 

300l Combi type thermal store. 

 

Rayburn on Gravity direct Circuit. 

Oil Boiler on pumped direct circuit. 

DHW coil with thermostatic mixing valve. 

Heating Coil to accommodate upstairs rads using existing F+E tank. 

 

All commentary welcome. 

 

 

[Spreadsheetman]

This reminded me of this blog  http://mydreamhouse.co.uk/exotic-heating-systems/ where a thermal store was used. Something called a Laddomat had to be added to make the stove bit work properly.

[dpmiller]

It's a similar scheme to my own, but as well as using a Laddomat-style load unit, I've also chosen to use a stove with a cooling coil in it for boil protection.

 

You might want to consider this safety aspect yourself- maybe using an STS valve to supply cold mains to the bottom of the store in the case of a catastrophic overheat?

[Nickfromwales]

I’ll need a pint in my hand before replying to this later. 
In the interim, is there 100% defo just the one header tank servicing the copper cylinder and Rayburn? Looks like it from the images, which send a shiver down the spine…….

[Iceverge]

Yup........"The Old Way" however with a non lined steel boiler = Brown DHW 🤢

 

[Iceverge]

6 hours ago, dpmiller said:

You might want to consider this safety aspect yourself- maybe using an STS valve to supply cold mains to the bottom of the store in the case of a catastrophic overheat?

 

No mains, just a pumped well so not an option in a powercut. 

[Nickfromwales]

Heat circuit input connections to the cylinder just look too close together…….

[Iceverge]

Maybe a primatic cylinder?