Options for fully pumped CH with minimal controls

I'm moving into a new house that I think has a fully pumped central heating system. The boiler is oil-fired. The system has minimal controls with no room thermostats or TRVs and a very simple timeswitch for the boiler. There is a manual ball valve to isolate the CH. (This very basic installatioon seems to be quite standard in this part of Ireland.)

Could anyone suggest any relatively easy ways to add more control to the system. How much benefit would adding TRV's alone be? Would adding a motorized valve in series with the CH ball valve and connected to a better timeswitch make sense. Should/can I go the whole way and add Y-Plan type controls.

I should probably point out that the system is brand new and just seems to be under-specced.

Thanks, Jonathan

Reply to
JonathanD
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That would be illegal in the UK, (I assume southern Ireland). Put in two

2-port zone valves (one CH, one DHW), cylinder stat, Honeywell CM67 (with optimisation) programmers/stat. Have a timer for the DHW only. Put TRVs on the rads except the one where the CM67 is. Find if the boiler requires a pump over-run and wire to suit.

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Reply to
IMM

Amazingly, I find myself in agreement with IMM! [I can't believe I'm writing this! Whatever happened to the expected response of "throw it all away and replace it with a combi"?]

I would just add one thing. If the boiler *does* need a pump over-run, the water needs somewhere to go during the over-run phase even if both zone valves are shut - which they likely will be. So install an automatic by-pass valve as well - between the flow and return pipes before the zone valves.

Reply to
Set Square

I am always right, so if you disagree accept you are wrong and do it my way.

Clombi's are banned in southern Ireland.

You have to look at the boiler makers specs.

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Reply to
IMM

If you are at the stage of deciding to put in controls then don't go for a Y plan but opt instead for an S-plan or a S+ if you can reasonably seperate upstairs and downstairs heating. This will depend on the pipework arrangement. Fit a "bypass" to the pipework before the motorised valves as this will provide a route for the pump to circulate in the event of closure of most of the TRVs, or short circuit failure of the microswitches in the valves. I've seen a few bathroom/cloakroom rads employed as a bypass route which gives dry towels all year. While drained down fit Danfoss TRVs to all radiators except the one in a "representative" position in the house, usually the hall for single heating zone houses but sometimes another room. Just avoid rooms with other heat sources such as kitchens and lounges with a fire. (You may find it beneficial if you have a towel rail as well as a bathroom rad then fit the rad with TRV and omit it from the towel rail.)

Presumably English building regs don't apply in your are then. dont you have something similar or does bureacracy give up in the face of intense blarney?

Reply to
John

It's not entirely in the spirit of the law here either! AFAIK, building regilations here state that there must be a reasonable level of control and then give guidelines in an appendix describing what "reasonable" might be. In theory the developer should have put in controls similar to your suggestion _and_ split the CH into two zones because the floor area is over a certain size. But that's one for the surveyors and solicitors to sort out :)

Thanks for the advice. If I can't get my way with the developer, it looks like I'll be getting my hands dirty. At least I have the opportunity to do the work before carpets etc. go in ;)

Jonathan

Reply to
JonathanD

Thanks for that -- reminded me to make sure I get all the specs from the developer.

Jonathan

Reply to
JonathanD

No, Ireland has strict building regulations - the degree to which they're applied just seems to be inversely proportional to the distance from Dublin :D

AFAIK, some of the regs covering insulation (U-valve and other things I haven't a clue about) are even stricter than the UK regs. Having good regs is only half the battle though ...

Jonathan

Reply to
JonathanD

Good idea to split into two zones, upstairs and down. Use another 2-port valve and CM67. It may be more pipework, and a bit of pain, but the house is empty and it is worth it.

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Reply to
IMM

UK regs on insulation is very high and increasing too. On Grand Designs on TV, they covered a converted church in Ireland and there was hardly any insulation in the place.

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Reply to
IMM

I saw that episode. There are exemptions for "buildings of architectural and historic interest" -- I guess the church came under that heading.

Under our 2002 regs, the _minimum_ level of control is (quiting from the regs) "automatic control of space heating on basis of room temperature; automatic control of heat input to stored hot water on basis of stored water temperature; separate and independent automatic time control of space heating and hot water; shut down of boiler or other heat source when there is no demand for either space or water heating from that source".

This sounds like what you've described, so I guess I'll be taking it up with the solicitors!

Reply to
JonathanD

I can't see why. They built a modern house inside the churrch. I would have filled that place as it was open to the elements.

Best of luck.

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Reply to
IMM

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember JonathanD saying something like:

That minimal installation is in 90% of houses here. It's inefficient and more costly to run in comparison with a properly laid-out system, as you probably know. The vast majority of these minimal control systems have been put in over the past 30 years, but a surprising number of new builds are equipped with them; simply because the developers know they can get away with it because the buyers don't know any better.

Certainly worth an argument if you quote chapter and verse of the regs. If he won't play along with you get onto the county BCO.

Reply to
Grimly Curmudgeon

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "IMM" saying something like:

No worse than the UK, in general.

Reply to
Grimly Curmudgeon

How long have they allowed mains pressure water? Obviously in older parts of cities I would assume they do not allow them. Many British cities would not even allow a multi-point. The newer areas were more than adequate, but they didn't want to set a precedence, so banned the lot. Many cities have uprated the water mains since.

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Reply to
Dr Evil

The CM67 (with optimisation) will not function coirrectly on a system with stored DHW unless the DHW timer is set to heat the water at different times to when the CH is likely to be running.

The CM67 is for combies.

Reply to
Zip 1

The CM67 is *not* exclusively for combies.

It is *preferable* to time HW and CH at different times. It is very easy to do this, by having HW on Timed - using the timer in the main programmer - and by having CH on Continuous, and actually timing it with the CM67.

If they are both on together, some of the boiler's output will be heating the water - so the rate of heatup of the house may be slightly lower than the CM67 assumes when determining when to start the heating. However, in my experience, the CM67 takes a slightly pessimistic view - and starts a bit early anyway - so this ain't going to matter too much.

Reply to
Set Square

Not exclusively. The CM67 is a single zone control and is fine for any system as long as you realise its limitations. To control hot water you need a seperate single output time control to take care of the cylinder. Use of more than one CM67 is OK for multi heating zone installations when you will gain its optimised start facility. In any case its a requirement to have seperate independant controls for time and temperature of heating and hot water. Hence old style single time zone programmers don't fit the bill any more although this doesn't seem to have filtered through to the world at large.

Reply to
John

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